1. 【命令】：cat

【功能说明】：

concatenate files and print on the standard output ＃连接文件并打印到标准输出，有标准输出的都可以用重定向定向导入到文件里面

【语法格式】：

cat [OPTION]...[FILE]...

【选项参数】：

参数	说明	简解
-b,--number-nonblank	number nonempty output lines	非空输出行编号
-n,--number	number all outputnlines	所有行输出编号

【示例】：

1、基本用法：查看文件内容

[root@oldboy ~]# cat /etc/passwd

root:x:0:0:root:/root:/bin/bash

bin:x:1:1:bin:/bin:/sbin/nologin

daemon:x:2:2:daemon:/sbin:/sbin/nologin

adm:x:3:4:adm:/var/adm:/sbin/nologin

lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

sync:x:5:0:sync:/sbin:/bin/sync

shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

2、把log1.txt的文件内容加上行号输入log2.txt这个文件里

[root@oldboy ~]# cat -n log1.txt

1 2012-1

2 2013-1

3 2014-1

[root@oldboy ~]# cat -n log1.txt>log2.txt

[root@oldboy ~]# cat log2.txt

1 2012-1

2 2013-1

3 2014-1

3、把文件log1.txt里面的文件空格不显示行号加入log2.txt中

[root@oldboy ~]# cat -n log1.txt

1 2012-1

2 2013-1

3 2014-1

[root@oldboy ~]# cat -b log1.txt

1 2012-1

2 2013-1

3 2014-1

[root@oldboy ~]# cat -b log1.txt>log2.txt

[root@oldboy ~]# cat log2.txt

1 2012-1

2 2013-1

3 2014-1

4、同时显示log1.txt和log2.txt

[root@oldboy ~]# cat log1.txt log2.txt

2012-1

2013-1

2014-1

1 2012-1

2 2013-1

3 2014-1

5、使用cat编辑文档内容

[root@oldboy ~]# cat >log1.txt<<EOF

> 2012-3

> 2013-3

> 2014-3

> EOF

[root@oldboy ~]# cat log1.txt

2012-3

2013-3

2014-3

6、使用cat追加编辑文档内容

[root@oldboy data]# cat >>oldboy.txt<<EOF

> ni hao

> jin tian tian qi zhen hao

> EOF

[root@oldboy data]# cat oldboy.txt

I am oldboy

I am study linux

ni hao

jin tian tian qi zhen hao

2. 【命令】：cd

【功能说明】：

Change the current directory to DIR ＃更改当前路径为DIR

【语法格式】：

cd [-L|-P] [dir]

【选项参数】：

参数	说明	简解
-L	force symbolic links to be followed
-P	use the physical directory structure without following symbolic
-

【示例】：

[root@oldboy ~]# cd /

[root@oldboy /]#

[root@oldboy ~]# cd ..

[root@oldboy /]#

[root@oldboy /]# cd -

/root

[root@oldboy ~]#

3. 【命令】：mkdir

【功能说明】：

make directories ＃创建目录

【语法格式】：

mkdir [OPTION]... DIRECTORY...

【选项参数】：

参数	说明	简解
-m, --mode	set file mode (as in chmod), not a=rwx - umask	设定权限<模式>（类似chmod），而不是rwxrwxrwx减umask
-p, --parents	no error if existing, make parent directories as needed	递归创建目录
-v, --verbose	print a message for each created directory	每次创建新目录都显示信息
-Z	set the SELinux security context of each created directory to CTX

【示例】：

1、基本用法：创建目录

[root@oldboy ~]# mkdir /data

[root@oldboy ~]# cd /data

[root@oldboy data]# pwd

/data

2、递归创建多个目录

[root@oldboy data]# mkdir -p /oldboy/oldboy

[root@oldboy data]# cd /oldboy/oldboy

[root@oldboy oldboy]# pwd

/oldboy/oldboy

4. 【命令】：ls

【功能说明】：

list directory contents #列出目标目录中所有的子目录和文件

【语法格式】：

ls [OPTION]... [FILE]...

【选项参数】：

参数	说明	简解
-a, --all	do not ignore entries starting with.	列出目录下的所有文件
-A, --almost-all	do not list implied.and ..	同-a，但不列出“.”(表示当前目录)和“..”(表示当前目录的父目录)
-b, --escape	print octal escapes for nongraphic characters	把文件名中不可输出的字符用反斜杠加字符编号的形式列出
-B, --ignore-backups	do not list implied entries ending with ~	不输出以“~”结尾的备份文件
-c	sort by ctime	配合-lt；根据ctime排序及显示ctime(文件状态最后更改的时间)配合-l：显示ctime但根据名称排序否则：根据ctime排序
-C	list entries by clumns	每栏由上至下列出项目
-d, --directory	list directory entries instead of contentsm,and do not dereference symbolic links	将目录象文件一样显示，而不是显示其下的文件
-D, --dired	generate output designed for Emacs’ dired mode	产生适合Emacs的dired模式使用的结果
-f	do not sort,enable -aU,disable -ls --color	对输出的文件不进行排序，-aU选项生效，-1st选项失效
-F --classify	append indicator(one of */=>@\|)to entries	在每个文件名后附上一个字符以说明该文件的类型，“*”表示可执行的普通文件；“/”表示目录；“@”表示符号链接；“\|”表示FIFOs；“=”表示套接字(sockets)
-g	like -l,but do not list owner	类似-l，但不列出所有者
-h, --human-readable	with -l,print sizes in human readable format	以容易理解的格式列出文件大小
-H, --dereference-command-line	follow symbolic links listed on the command line	使用命令列中的符号链接指示的真正目的地
-i, --inode	print the index number of each file	打印出每个文件的inode号
-I,--ignore=PATTERN	do not list implied entries matching shell PATTERN	不打印出任何符合shell万用字符<样式>的项目
-k	like --block-size=1K	以k字节的形式表示文件的大小
-l	use a long listing format	除了文件名之外，还将文件的权限、所有者、文件大小等信息详细列出来
-L,--dereference	when showing file information for a symbolic link,show information for the file the link references rather than for the link itself	当显示符号链接的文件信息时，显示符号链接所指示的对象而并非符号链接本身的信息。
-m	fill width with a comma separated list of entries	所有项目以逗号分隔，并填满整行行宽
-n, --numeric-uid-gid	like -l,but list numeric user and group IDs	用数字的UID，GID代替名称
-N, --literal	print raw entry names	不限制文件长度
-o	like -l,but do not list group information	类似-l，显示文件的除组信息外的详细信息
-p, --indicator-style=slash	append / indicator to directories	对目录添加“/”符号
-q, --hide-control-chars	print ? instead of non graphic characters	用？号代替不可输出的字符
-Q, --quote-name	enclose entry names in double quotes	把输出的文件名用双引号括起来
-r, --reverse	reverse order while sorting	依相反次序排列
-R, --recursive	list subdirectories recursively	同时列出所有子目录层
-s, --size	print the allocated size of each file,in blocks	以块大小为单位列出所有文件的大小
-S	sort by file size	根据文件大小排序
-t	sort by modification time	以文件修改时间排序
-T, --tabsize=COLS	assume tab stops at each COLS instead of 8
-u	with -lt: sort by, and show, access time with -l:show access time and sort by name otherwise: sort by access time	配合-lt:显示访问时间而且依访问时间排序配合-l：显示访问时间但根据名称排序其他：根据访问时间排序
-U	do not sort; list entries in directory order	不进行排序；依文件系统原有的次序列出项目
-v	natural sort of (version) numbers within text	根据版本进行排序
-w, --width=COLS	assume screen width instead of current value	自行指定屏幕宽度而不使用目前的数值
-x	list entries by lines instead of by columns	逐行列出项目而不是逐栏列出
-X	sort alphabetically by entry extension	根据扩展名排序
-1	list one file per line	每行只列出一个文件

【示例】：

1、基本用法：查看目录内容

[root@oldboy ~]# ls

anaconda-ks.cfg data install.log install.log.syslog log1.txt log2.txt test.txt

2、基本用法：查看目录全部内容（包含隐藏文件）

[root@oldboy ~]# ls -la

total 88

dr-xr-x---. 3 root root 4096 Mar 7 18:16 .

dr-xr-xr-x. 24 root root 4096 Mar 9 17:00 ..

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

-rw-------. 1 root root 5003 Mar 9 04:13 .bash_history

-rw-r--r--. 1 root root 18 May 20 2009 .bash_logout

-rw-r--r--. 1 root root 176 May 20 2009 .bash_profile

-rw-r--r--. 1 root root 176 Sep 23 2004 .bashrc

-rw-r--r--. 1 root root 100 Sep 23 2004 .cshrc

drwxr-xr-x. 3 root root 4096 Mar 9 01:47 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

-rw-r--r--. 1 root root 5890 Mar 3 23:13 install.log.syslog

-rw-r--r--. 1 root root 18 Mar 7 18:13 log1.txt

-rw-r--r--. 1 root root 44 Mar 7 17:53 log2.txt

-rw-r--r--. 1 root root 129 Dec 4 2004 .tcshrc

-rw-r--r--. 1 root root 0 Mar 7 18:27 test.txt

3、基本用法：查看目录（使用长模式）

[root@oldboy ~]# ls -l

total 52

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

drwxr-xr-x. 3 root root 4096 Mar 9 01:47 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

-rw-r--r--. 1 root root 5890 Mar 3 23:13 install.log.syslog

-rw-r--r--. 1 root root 18 Mar 7 18:13 log1.txt

-rw-r--r--. 1 root root 44 Mar 7 17:53 log2.txt

-rw-r--r--. 1 root root 0 Mar 7 18:27 test.txt

5. 【命令】：pwd

【功能说明】：

print name of current/working directory ＃打印当前目录路径

【语法格式】：

pwd [OPTION]

【选项参数】：

参数	说明	简解
-L, --logical	use PWD from environment,even if it contains symlinks	当目录为链接路径时，显示链接路径
-P, --physical	avoid all symlinks	显示实际物理路径，而非使用链接

【示例】：

1、基本用法：显示当前目录所在路径

[root@oldboy ~]# pwd

/root

[root@oldboy ~]#

2、显示当前目录的物理路径

[root@oldboy ~]# cd /etc/init.d

[root@oldboy init.d]# pwd -P

/etc/rc.d/init.d

3、显示当前目录的链接路径

[root@oldboy ~]# cd /etc/init.d

[root@oldboy init.d]# pwd -L

/etc/init.d

6. 【命令】：touch

【功能说明】：

change file timestamps ＃创建文件或改变文件的时间戳

【语法格式】：

pwd [OPTION]... FILE...

【选项参数】：

参数	说明	简解
-a	change only the access time	只更改存取时间
-c, --no-create	do not create any files	不新建任何文档
-d, --date=STRING	parse STRING and use it instead of current time	使用指定的日期时间，而非现在的时间
-f	(ignored)	忽略
-h, --no-dereference	affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink)	会影响符号链接本身，而非符号链接所指示的目的地
-m	change only the modification time	只更改变动时间
-r, --reference=FILE	use this file’s times instead of current time	把指定文档或目录的日期时间，统统设成和参考文档或目录的日期时间相同
-t STAMP	use [[CC]YY]MMDDhhmm[.ss] instead of current time	使用指定格式的日期时间，而非当前时间
--time=WORD	change the specified time: WORD is access, atime, or use: equivalent to -a WORD is modify or mtime: equivalent to -m	使用WORD指定的时间：access、atime、use都等于-a选项的效果，而modify、mtime等于-m选项的效果

【示例】：

1、基本用法：创建新文件

[root@oldboy data]# touch log2012.log log2013.log

[root@oldboy data]# ll

total 0

-rw-r--r--. 1 root root 0 Mar 9 17:48 log2012.log

-rw-r--r--. 1 root root 0 Mar 9 17:48 log2013.log

2、不创建不存在的文件

[root@oldboy data]# touch -c log2014.log

[root@oldboy data]# ll

total 0

-rw-r--r--. 1 root root 0 Mar 9 17:48 log2012.log

-rw-r--r--. 1 root root 0 Mar 9 17:48 log2013.log

3、更新log2012.log的时间和log.log时间戳相同

[root@oldboy data]# touch log.log

[root@oldboy data]# ll

total 0

-rw-r--r--. 1 root root 0 Mar 9 2016 log2012.log

-rw-r--r--. 1 root root 0 Mar 9 2016 log2013.log

-rw-r--r--. 1 root root 0 May 23 00:00 log.log

[root@oldboy data]# touch -r log.log log2012.log

[root@oldboy data]# ll

total 0

-rw-r--r--. 1 root root 0 May 23 00:00 log2012.log

-rw-r--r--. 1 root root 0 Mar 9 2016 log2013.log

-rw-r--r--. 1 root root 0 May 23 00:00 log.log

4、设定文件时间戳

[root@oldboy data]# touch -t 201211142234.50 log2016.log

[root@oldboy data]# ll

total 0

-rw-r--r--. 1 root root 0 Nov 14 2012 log2016.log

【说明】：

-t time 使用指定的时间值 time 作为指定文件相应时间戳记的新值．此处的 time规定为如下形式的十进制数:

[[CC]YY]MMDDhhmm[.SS]

这里，CC为年数中的前两位，即”世纪数”；YY为年数的后两位，即某世纪中的年数．如果不给出CC的值，则touch 将把年数CCYY限定在1969--2068之内．MM为月数，DD为天将把年数CCYY限定在1969--2068之内．MM为月数，DD为天数，hh 为小时数(几点)，mm为分钟数，SS为秒数．此处秒的设定范围是0--61，这样可以处理闰秒．这些数字组成的时间是环境变量TZ指定的时区中的一个时间．由于系统的限制，早于1970年1月1日的时间是错误的。

7. 【命令】：echo

【功能说明】：

display a line of text ＃打印输出

【语法格式】：

echo [SHORT-OPTION]... [STRING]...

echo LONG-OPTION

【选项参数】：

参数	说明	简解
-n	do not output the trailing newline	不要在最后自动换行
-e	enable interpretation of backslash escapes	若字符串中出现以下字符，则特别加以处理，而不会将它当成一般文字输出 \a 发出警告声； \b 删除前一个字符； \c 最后不加上换行符号； \f 换行但光标仍旧停留在原来的位置； \n 换行且光标移至行首； \r 光标移至行首，但不换行； \t 插入tab； \v 与\f相同； \\ 插入\字符； \nnn 插入nnn（八进制）所代表的ASCII字符；
-E	disable interpretation of backslash escapes (default)	不解释转意字符

【示例】：

1、基本用法：打印内容

[root@oldboy data]# echo "I am studying linux."

I am studying linux.

2、打印变量内容

[root@oldboy data]# echo $PATH

/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

8. 【命令】：xargs

【功能说明】：

build and execute command lines from standard input ＃从标准输入获取内容创建和执行命令

【语法格式】：

xargs [-0prtx] [-E eof-str] [-e[eof-str]] [--eof[=eof-str]] [--null] [-d delimiter]

[--delimiter delimiter] [-I replace-str] [-i[replace-str]] [--replace[=replace-str]]

[-l[max-lines]] [-L max-lines] [--max-lines[=max-lines]] [-n max-args] [--max-args=max-

args] [-s max-chars] [--max-chars=max-chars] [-P max-procs] [--max-procs=max-procs]

[--interactive] [--verbose] [--exit] [--no-run-if-empty] [--arg-file=file]

[--show-limits] [--version] [--help] [command [initial-arguments]]

【选项参数】：

参数	说明	简解

【示例】：

1、基本用法：与find配合使用，删除/data目录下所有.txt文件

[root@oldboy ~]# find /data -type f -name "*.txt"|xargs rm -f

[root@oldboy ~]# cd /data

[root@oldboy data]# ll

total 0

9. 【命令】：mv

【功能说明】：

move (rename) files ＃移动或重命名文件

【语法格式】：

mv [OPTION]... [-T] SOURCE DEST

mv [OPTION]... SOURCE... DIRECTORY

mv [OPTION]... -t DIRECTORY SOURCE...

【选项参数】：

参数	说明	简解
--backup[=CONTROL]	make a backup of each existing destination file	备份模式：若需覆盖文件，则覆盖前先行备份
-b	like --backup but does not accept an argument	若需覆盖文件，则覆盖前先行备份。
-f, --force	do not prompt before overwriting	force 强制的意思，如果目标文件已经存在，不会询问而直接覆盖
-i, --interactive	prompt before overwrite	若目标文件 (destination) 已经存在时，就会询问是否覆盖
-n, --no-clobber	do not overwrite an existing file
-S, --suffix=SUFFIX	override the usual backup suffix	为备份文件指定后缀，而不使用默认的后缀；
-t, --target-directory=DIRECTORY	move all SOURCE arguments into DIRECTORY	指定mv的目标目录，该选项适用于移动多个源文件到一个目录的情况，此时目标目录在前，源文件在后
-T, --no-target-directory	treat DEST as a normal file
-u, --update	move only when the SOURCE file is newer than the destination file or when the destination file is missing	若目标文件已经存在，且 source 比较新，才会更新(update)
-v, --verbose	explain what is being done	显示程序执行过程

【示例】：

1、基本用法：移动文件

[root@oldboy ~]# mv ett.txt /root/data

[root@oldboy ~]# cd data

[root@oldboy data]# ll

total 4

-rw-r--r--. 1 root root 292 Mar 9 13:28 ett.txt

2、基本用法：移动目录

[root@oldboy ~]# mv /data /root

[root@oldboy ~]# ll

total 56

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

drwxr-xr-x. 2 root root 4096 Mar 9 13:56 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

3、更改文件名

[root@oldboy data]# ll

total 4

-rw-r--r--. 1 root root 292 Mar 9 13:28 ett.txt

[root@oldboy data]# mv ett.txt oldboy.txt

[root@oldboy data]# ll

total 4

-rw-r--r--. 1 root root 292 Mar 9 13:28 oldboy.txt

4、多个文件移动到同一个目录

[root@localhost test3]# mv -t /opt/soft/test/test4/ log1.txt log2.txt log3.txt

[root@localhost test3]# cd ..

[root@localhost test]# cd test4/

[root@localhost test4]# ll

总计 12

-rw-r--r-- 1 root root 8 10-28 06:15 log1.txt

-rw-r--r-- 1 root root 12 10-28 06:15 log2.txt

-rw-r--r-- 1 root root 13 10-28 06:16 log3.txt

10. 【命令】：rm

【功能说明】：

remove files or directories ＃移除文件或目录

【语法格式】：

rm [OPTION]... FILE...

【选项参数】：

参数	说明	简解
-f, --force	ignore nonexistent files,never prompt	忽略不存在的文件，从不给出提示
-i	prompt before every removal	进行交互式删除
-I	prompt once before removing more than three files, or when removing recursively. Less intrusive than -i, while still giving protection against most mistakes
-r, -R, --recursive	remove directories and their contents recursively	指示rm将参数中列出的全部目录和子目录均递归地删除
-v, --verbose	explain what is being done	显示命令执行过程

【示例】：

1、基本用法：删除文件

[root@oldboy ~]# rm log1.txt

rm: remove regular file `log1.txt'? y

[root@oldboy ~]# ll

total 52

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

drwxr-xr-x. 2 root root 4096 Mar 9 13:56 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

-rw-r--r--. 1 root root 5890 Mar 3 23:13 install.log.syslog

-rw-r--r--. 1 root root 44 Mar 7 17:53 log2.txt

-rw-r--r--. 1 root root 18 Mar 9 13:19 oldboy.txt

2、基本用法：删除目录

[root@oldboy data]# rm -r a

rm: descend into directory `a'? y

rm: descend into directory `a/b'? y

rm: remove regular empty file `a/b/oldboy.txt'? y

rm: remove directory `a/b/c'? y

rm: remove directory `a/b'? y

rm: remove regular empty file `a/oldboy.txt'? y

rm: remove directory `a'? y

11. 【命令】：find

【功能说明】：

search for files in a directory hierarchy ＃查找文档

【语法格式】：

find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]

【选项参数】：

参数或选项	说明	简解
-atime n	File was last accessed n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago.	根据最后一次的访问时间查找文件
-ctime n	File’s status was last changed n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times.	根据最后一次的改变时间查找文件
-mtime n	File’s data was last modified n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file modification times.	根据最后一次的修改时间查找文件
-type c	File is of type c: b block (buffered) special c character (unbuffered) special d directory p named pipe (FIFO) f regular file l symbolic link; this is never true if the -L option or the -follow option is in effect, unless the symbolic link is broken. If you want to search for symbolic links when -L is in effect, use -xtype. s socket D door (Solaris)	查找某一类型的文件 b 块设备文件 d 目录 c 字符设备文件 p 管道文件 l 符号链接文件 f 普通文件 s socket文件
-name pattern	Base of file name (the path with the leading directories removed) matches shell pattern pattern. The metacharacters (‘*’, ‘?’, and ‘[]’) match a ‘.’ at the start of the base name (this is a change in findutils-4.2.2; see section STAN-DARDS CONFORMANCE below). To ignore a directory and the files under it, use -prune; see an example in the description of -path. Braces are not recognised as being special, despite the fact that some shells including Bash imbue braces with a special meaning in shell patterns. The filename matching is performed with the use of the fnmatch(3) library function. Don’t forget to enclose the pattern in quotes in order to protect it from expansion by the shell.	按文件名查找文件
-perm mode	File’s permission bits are exactly mode (octal or symbolic). Since an exact match is required, if you want to use this form for symbolic modes, you may have to specify a rather complex mode string. For example ‘-perm g=w’ will only match files which have mode 0020 (that is, ones for which group write permission is the only permission set). It is more likely that you will want to use the ‘/’ or ‘-’ forms, for example ‘-perm -g=w’, which matches any file with group write permis- sion. See the EXAMPLES section for some illustrative examples.	按照文件权限来查找文件
-size n[cwbkMG]	File uses n units of space. The following suffixes can be used: ‘b’ for 512-byte blocks (this is the default if no suffix is used) ‘c’ for bytes ‘w’ for two-byte words ‘k’ for Kilobytes (units of 1024 bytes) ‘M’ for Megabytes (units of 1048576 bytes) ‘G’ for Gigabytes (units of 1073741824 bytes)	按大小查找

【示例】：

1、基本用法：按文件名查找文件

[root@oldboy ~]# find /root/data -name "*.txt"

/root/data/oldboy.txt

2、基本用法：按文件类型查找文件

[root@oldboy ~]# find /root/data -type f

/root/data/oldboy.txt

3、查找文件名称不为oldboy.txt的所有文件

[root@oldboy ~]# ll

total 52

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

drwxr-xr-x. 2 root root 4096 Mar 9 15:09 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

-rw-r--r--. 1 root root 5890 Mar 3 23:13 install.log.syslog

-rw-r--r--. 1 root root 44 Mar 7 17:53 log2.txt

-rw-r--r--. 1 root root 18 Mar 9 13:19 oldboy.txt

[root@oldboy ~]# find /root ! -name "oldboy.txt"

/root

/root/.bash_history

/root/.bashrc

/root/.bash_logout

/root/.bash_profile

/root/data

/root/install.log

/root/log2.txt

/root/.lesshst

/root/.cshrc

/root/anaconda-ks.cfg

/root/install.log.syslog

/root/.tcshrc

4、利用find查找删除扩展名为txt的所有文件

[root@oldboy data]# ll

total 4

-rw-r--r--. 1 root root 0 Mar 9 16:13 1.txt

-rw-r--r--. 1 root root 0 Mar 9 16:13 2.txt

-rw-r--r--. 1 root root 0 Mar 9 16:13 3.txt

-rw-r--r--. 1 root root 292 Mar 9 13:28 oldboy.txt

[root@oldboy data]# find /root/data -type f -name "*.txt"|xargs rm -f

[root@oldboy data]# ll

total 0

【说明】：

1、按修改时间查找文件，+7表示距今天7天以前，7表示距今天整7天，-7表示最近7天

2、-o表示或者的意思，-a表示并且的意思，！表示取反

12. 【命令】：grep

【功能说明】：

print lines matching a pattern ＃用于过滤、搜索特定字符

【语法格式】：

grep [OPTIONS] PATTERN [FILE...]

grep [OPTIONS] [-e PATTERN | -f FILE] [FILE...]

【选项参数】：

参数	说明	简解
-a, --text	Process a binary file as if it were text; this is equivalent to the --binary-files=text option.	不要忽略二进制的数据
-A NUM , --after-context=NUM	Print NUM lines of trailing context after matching lines. Places a line containing a group separator (described under --group-separator) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given.	除了显示符合范本样式的那一列之外，并显示该行之后的内容
-b, --byte-offset	Print the 0-based byte offset within the input file before each line of output. If -o (--only-matching) is specified, print the offset of the matching part itself.	在显示符合样式的那一行之前，标示出该行第一个字符的编号
-B NUM, --before-context=NUM	Print NUM lines of leading context before matching lines. Places a line containing a group separator (described under --group-separator) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given.	除了显示符合样式的那一行之外，并显示该行之前的内容
-c, --count	Suppress normal output; instead print a count of matching lines for each input file. With the -v, --invert-match option (see below), count non-matching lines. (-c is specified by POSIX.)	计算符合样式的列数
-C NUM, -NUM, --context=NUM	Print NUM lines of output context. Places a line containing a group separator (described under --group-separator) between contiguous groups of matches. With the -o or --only-matching option, this has no effect and a warning is given.	除了显示符合样式的那一行之外，并显示该行之前后各n行内容
-d ACTION, --directories=ACTION	If an input file is a directory, use ACTION to process it. By default, ACTION is read, i.e., read directories just as if they were ordinary files. If ACTION is skip, silently skip directories. If ACTION is recurse, read all files under each directory, recursively, following symbolic links only if they are on the command line. This is equivalent to the -r option.	当指定要查找的是目录而非文件时，必须使用这项参数，否则grep指令将回报信息并停止动作。
-e PATTERN, --regexp=PATTERN	Use PATTERN as the pattern. This can be used to specify multiple search patterns, or to protect a pattern beginning with a hyphen (-). (-e is specified by POSIX.)	使用正则表达式
-E, --extended-regexp	Interpret PATTERN as an extended regular expression (ERE, see below). (-E is specified by POSIX.)	使用拓展的正则表达式
-f FILE, --file=FILE	Obtain patterns from FILE, one per line. The empty file contains zero patterns, and therefore matches nothing. (-f is specified by POSIX.)	指定规则文件，其内容含有一个或多个规则样式，让grep查找符合规则条件的文件内容，格式为每行一个规则样式。
-h, --no-filename	Suppress the prefixing of file names on output. This is the default when there is only one file (or only standard input) to search.	在显示符合样式的那一行之前，不标示该行所属的文件名称。
-H, --with-filename	Print the file name for each match. This is the default when there is more than one file to search.	在显示符合样式的那一行之前，表示该行所属的文件名称。
-i, --ignore-case	Ignore case distinctions in both the PATTERN and the input files. (-i is specified by POSIX.)	忽略字符大小写的差别。
-l, --files-with-matches	Suppress normal output; instead print the name of each input file from which output would normally have been printed. The scanning will stop on the first match. (-l is specified by POSIX.)	列出文件内容符合指定的样式的文件名称。
-L, --files-without-match	Suppress normal output; instead print the name of each input file from which no output would normally have been printed. The scanning will stop on the first match.	列出文件内容不符合指定的样式的文件名称。
-n, --line-number	Prefix each line of output with the 1-based line number within its input file. (-n is specified by POSIX.)	在显示符合样式的那一行之前，标示出该行的列数编号。
-q, --quiet, --silent	Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or --no-messages option. (-q is specified by POSIX.)	不显示任何信息。
-r, --recursive	Read all files under each directory, recursively, following symbolic links only if they are on the command line. This is equivalent to the -d recurse option.	如果文件参数是目录，该选项将递归搜索该目录下的所有子目录和文件。同-R
-s, --no-messages	Suppress error messages about nonexistent or unreadable files. Portability note: unlike GNU grep, 7th Edition Unix grep did not conform to POSIX, because it lacked -q and its -s option behaved like GNU grep’s -q option. USG-style grep also lacked -q but its -s option behaved like GNU grep. Portable shell scripts should avoid both -q and -s and should redirect standard and error output to /dev/null instead. (-s is specified by POSIX.)	不显示错误信息。
-v, --invert-match	Invert the sense of matching, to select non-matching lines. (-v is specified by POSIX.)	显示不包含匹配文本的所有行。
-V, --version	Print the version number of grep to the standard output stream. This version number should be included in all bug reports (see below).	显示版本信息。
-w, --word-regexp	Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word- constituent characters are letters, digits, and the underscore.	只显示完整单词的匹配
-x, --line-regexp	Select only those matches that exactly match the whole line. (-x is specified by POSIX.)	只显示完整行的匹配

【示例】：

1、基本用法：显示文件中包含字符串的行

[root@oldboy ~]# cat oldboy.txt

test

liyao

oldboy

[root@oldboy ~]# grep "oldboy" oldboy.txt

oldboy

[root@oldboy ~]#

2、基本用法：显示文件中不包含字符串的行

[root@oldboy ~]# grep -v "oldboy" oldboy.txt

test

liyao

3、除了显示匹配的一行外，并显示该行之后的n行

[root@oldboy ~]# grep 20 -A 10 test.txt

【说明】：

grep的正则表达式:

^ #锚定行的开始如：'^grep'匹配所有以grep开头的行。

$ #锚定行的结束如：'grep$'匹配所有以grep结尾的行。

. #匹配一个非换行符的字符如：'gr.p'匹配gr后接一个任意字符，然后是p。

* #匹配零个或多个先前字符如：'*grep'匹配所有一个或多个空格后紧跟grep的行。

.* #一起用代表任意字符。

[] #匹配一个指定范围内的字符，如'[Gg]rep'匹配Grep和grep。

[^] #匹配一个不在指定范围内的字符，如：'[^A-FH-Z]rep'匹配不包含A-R和T-Z的一个字母开头，紧跟rep的行。

$..$ #标记匹配字符，如'$love$'，love被标记为1。

\< #锚定单词的开始，如:'\<grep'匹配包含以grep开头的单词的行。

\> #锚定单词的结束，如'grep\>'匹配包含以grep结尾的单词的行。

x\{m\} #重复字符x，m次，如：'0\{5\}'匹配包含5个o的行。

x\{m,\} #重复字符x,至少m次，如：'o\{5,\}'匹配至少有5个o的行。

x\{m,n\} #重复字符x，至少m次，不多于n次，如：'o\{5,10\}'匹配5--10个o的行。

\w #匹配文字和数字字符，也就是[A-Za-z0-9]，如：'G\w*p'匹配以G后跟零个或多个文字或数字字符，然后是p。

\W #\w的反置形式，匹配一个或多个非单词字符，如点号句号等。

\b #单词锁定符，如: '\bgrep\b'只匹配grep。

POSIX字符:

为了在不同国家的字符编码中保持一至，POSIX(The Portable Operating System Interface)增加了特殊的字符类，如[:alnum:]是[A-Za-z0-9]的另一个写法。要把它们放到[]号内才能成为正则表达式，如[A- Za-z0-9]或[[:alnum:]]。在linux下的grep除fgrep外，都支持POSIX的字符类。

[:alnum:] #文字数字字符

[:alpha:] #文字字符

[:digit:] #数字字符

[:graph:] #非空字符（非空格、控制字符）

[:lower:] #小写字符

[:cntrl:] #控制字符

[:print:] #非空字符（包括空格）

[:punct:] #标点符号

[:space:] #所有空白字符（新行，空格，制表符）

[:upper:] #大写字符

[:xdigit:] #十六进制数字（0-9，a-f，A-F）

13. 【命令】：head

【功能说明】：

output the first part of files ＃打印文件的前几行

【语法格式】：

head [OPTION]... [FILE]...

【选项参数】：

参数	说明	简解
-c, --bytes=[-]K	print the first K bytes of each file; with the leading ‘-’,print all but the last K bytes of each file	按前K字节打印文件
-n, --lines=[-]K	print the first K lines instead of the first 10; with the leading ‘-’, print all but the last K lines of each file	按前K行打印文件
-q, --quiet, --silent	never print headers giving file names	隐藏文件名
-v, --verbose	always print headers giving file names	显示文件名

【示例】：

1、基本用法：打印文件前几行

[root@oldboy ~]# head -n 13 test.txt

2、打印文件前K个字节

[root@oldboy ~]# head -c 20 test.txt

10[root@oldboy ~]#

3、显示文件名

[root@oldboy ~]# head -v test.txt

==> test.txt <==

14. 【命令】：cp

【功能说明】：

copy files and directories ＃复制文件或目录

【语法格式】：

cp [OPTION]... [-T] SOURCE DEST

cp [OPTION]... SOURCE... DIRECTORY

cp [OPTION]... -t DIRECTORY SOURCE...

【选项参数】：

参数	说明	简解
-a, --archive	same as -dR --preserve=all	保持源文件的原有结构和属性，与选项“-dpR”相同
--backup[=CONTROL]	make a backup of each existing destination file	做一个已存在文件的备份
-b	like --backup but does not accept an argument	覆盖已存在的目标文件前将目标文件备份
--copy-contents	copy contents of special files when recursive
-d	same as --no-dereference --preserve=links	如果复制的源文件是符号链接，仅复制符号链接本身，而且保留符号链接所指向的目标文件或目录
-f, --force	if an existing destination file cannot be opened, remove it and try again (redundant if the -n option is used)	强制覆盖已经存在的目标文件，不提示用户确认
-i, --interactive	prompt before overwrite (overrides a previous -n option)	在覆盖已存在的目标文件前提示用户进行确认
-H	follow command-line symbolic links in SOURCE
-l, --link	link files instead of copying	为源文件创建硬链接
-L, --dereference	always follow symbolic links in SOURCE
-n, --no-clobber	do not overwrite an existing file (overrides a previous -i option)
-P, --no-dereference	never follow symbolic links in SOURCE
-p	same as --preserve=mode,ownership,timestamps	复制文件时保持源文件的所有者、权限信息以及时间属性
--preserve[=ATTR_LIST]	preserve the specified attributes (default: mode,owner-ship,timestamps), if possible additional attributes: context, links, xattr, all
-c	same as --preserve=context
--no-preserve=ATTR_LIST	don’t preserve the specified attributes
--parents	use full source file name under DIRECTORY
-R, -r, --recursive	copy directories recursively	对目录进行复制操作，采用递归的操作方式
--reflink[=WHEN]	control clone/CoW copies. See below.
--remove-destination	remove each existing destination file before attempting to open it (contrast with --force)
--sparse=WHEN	control creation of sparse files. See below.
--strip-trailing-slashes	remove any trailing slashes from each SOURCE argument
-s, --symbolic-link	make symbolic links instead of copying	为源文件创建符号链接
-S, --suffix=SUFFIX	override the usual backup suffix	在备份文件时，用指定的后缀“SUFFIX”代替文件名的默认后缀
-t, --target-directory=DIRECTORY	copy all SOURCE arguments into DIRECTORY
-T, --no-target-directory	treat DEST as a normal file
-u, --update	copy only when the SOURCE file is newer than the destination file or when the destination file is missing	当目标文件不存在或者源文件比目标文件新时才进行复制操作
-v, --verbose	explain what is being done	详细显示指令执行的操作
-x, --one-file-system	stay on this file system	复制的文件或目录存放的文件系统，必须与cp指令执行时所处的文件系统相同，否则不复制，亦不处理位于其他分区的文件
-Z, --context=CONTEXT	set security context of copy to CONTEXT

【示例】：

1、基本用法：复制文件到指定位置

[root@oldboy ~]# cp test.txt data

[root@oldboy ~]# cat data/test.txt

2、基本用法：复制目录到指定位置

[root@oldboy ~]# cp -r /root/data /tmp

[root@oldboy ~]# cd /tmp/data

[root@oldboy data]#

3、复制时保持文件属性

[root@oldboy ~]# ll

total 56

-rw-------. 1 root root 1079 Mar 3 23:14 anaconda-ks.cfg

drwxr-xr-x. 7 root root 4096 Mar 13 16:25 data

-rw-r--r--. 1 root root 22179 Mar 3 23:14 install.log

-rw-r--r--. 1 root root 5890 Mar 3 23:13 install.log.syslog

-rw-r--r--. 1 root root 44 Mar 7 17:53 log2.txt

-rw-r--r--. 1 root root 18 Mar 9 13:19 oldboy.txt

-rw-r--r--. 1 root root 292 Mar 13 15:13 test.txt

[root@oldboy ~]# cp -p test.txt /tmp

[root@oldboy ~]# ll /tmp

total 108

drwxr-xr-x 7 root root 4096 Mar 13 16:28 data

-rw-r--r-- 1 root root 292 Mar 13 15:13 test.txt

-rw-------. 1 root root 0 Mar 3 23:09 yum.log

-rw-------. 1 root root 100203 Mar 4 00:39 yum_save_tx-2016-03-04-00-39i_5ZVm.yumtx

15. 【命令】：tail

【功能说明】：

output the last part of files ＃打印文件末尾几行

【语法格式】：

tail [OPTION]... [FILE]...

【选项参数】：

参数	说明	简解
-c, --bytes=K	output the last K bytes; alternatively, use -c +K to output bytes starting with the Kth of each file	输出文件尾部的N个字节内容
-f, --follow[={name\|descriptor}]	output appended data as the file grows; -f, --follow, and --follow=descriptor are equivalent	显示文件最新追加的内容
-F	same as --follow=name --retry	与选项“--follow=name”和“--retry”连用时的功能相同
-n, --lines=K	output the last K lines, instead of the last 10; or use -n +K to output lines starting with the Kth	输出文件尾部K行内容
--max-unchanged-stats=N	with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files). With inotify, this option is rarely useful.	参看texinfo文档(默认为5)
--pid=PID	with -f, terminate after process ID, PID dies	与-f合用,表示在进程ID,PID死掉之后结束
-q, --quiet, --silent	never output headers giving file names	不显示文件名
--retry	keep trying to open a file even when it is or becomes inacces-sible; useful when following by name, i.e., with --follow=name	即使文件不可访问或者文件稍后变得不可访问，都始终尝试打开文件
-s, --sleep-interval=N	with -f, sleep for approximately N seconds (default 1.0) between iterations. With inotify and --pid=P, check process P at least once every N seconds.	与“-f”连用，指定监视文件变化时间所间隔的秒数
-v, --verbose	always output headers giving file names	总在开头显示文件名

【示例】：

1、基本用法：显示文件末尾的n行

[root@oldboy ~]# tail -8 test.txt

100

2、在开头显示文件名

[root@oldboy ~]# tail -v -n 8 test.txt

==> test.txt <==

100

16. 【命令】：alias

【功能说明】：

Define or display aliases. ＃显示或设置别名

【语法格式】：

alias [-p] [name[=value] ... ]

【选项参数】：

参数	说明	简解
-p	Print all defined aliases in a reusable format	打印已经设置的命令别名

【示例】：

1、基本用法：打印已经设置的别名（-p可以省略）

[root@oldboy ~]# alias -p

alias cp='cp -i'

alias l.='ls -d .* --color=auto'

alias ll='ls -l --color=auto'

alias ls='ls --color=auto'

alias mv='mv -i'

alias rm='rm -i'

alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

2、基本用法：设置新别名

[root@oldboy ~]# alias rm='echo "Do not use rm!"'

[root@oldboy ~]# rm -f test.txt

Do not use rm! -f test.txt

[root@oldboy ~]# alias

alias cp='cp -i'

alias l.='ls -d .* --color=auto'

alias ll='ls -l --color=auto'

alias ls='ls --color=auto'

alias mv='mv -i'

alias rm='echo "Do not use rm!"'

alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

17. 【命令】：unalias

【功能说明】：

Remove each NAME from the list of defined aliases. ＃取消别名

【语法格式】：

unalias [-a] name [name ...]

【选项参数】：

参数	说明	简解
-a	remove all alias definitions.	取消所有别名

【示例】：

1、基本用法：取消别名

[root@oldboy ~]# alias

alias cp='cp -i'

alias l.='ls -d .* --color=auto'

alias ll='ls -l --color=auto'

alias ls='ls --color=auto'

alias mv='mv -i'

alias rm='echo "Do not use rm!"'

alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

[root@oldboy ~]# unalias rm

[root@oldboy ~]# alias

alias cp='cp -i'

alias l.='ls -d .* --color=auto'

alias ll='ls -l --color=auto'

alias ls='ls --color=auto'

alias mv='mv -i'

alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

2、取消所有别名

[root@oldboy ~]# alias

alias cp='cp -i'

alias l.='ls -d .* --color=auto'

alias ll='ls -l --color=auto'

alias ls='ls --color=auto'

alias mv='mv -i'

alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

[root@oldboy ~]# unalias -a

[root@oldboy ~]# alias

[root@oldboy ~]#

18. 【命令】：seq

【功能说明】：

print a sequence of numbers ＃生成数字序列

【语法格式】：

seq [OPTION]... LAST

seq [OPTION]... FIRST LAST

seq [OPTION]... FIRST INCREMENT LAST

【选项参数】：

参数	说明	简解
-f, --format=FORMAT	use printf style floating-point FORMAT	格式化输出
-s, --separator=STRING	use STRING to separate numbers (default: \n)	指定分隔符，默认是换行符
-w, --equal-width	equalize width by padding with leading zeroes	输出同宽数列，不足的位数用0补齐

【示例】：

1、基本用法：生成数字序列

[root@oldboy ~]# seq 10

2、格式化输出

[root@oldboy ~]# seq -f 100%g 10

1001

1002

1003

1004

1005

1006

1007

1008

1009

10010

3、指定分隔符

[root@oldboy ~]# seq -s "..." 10

1...2...3...4...5...6...7...8...9...10

[root@oldboy ~]#

4、输出同宽数列

[root@oldboy ~]# seq -w 10

19. 【命令】：sed

【功能说明】：

stream editor for filtering and transforming text ＃用于过滤和转化文本的流编辑器

【语法格式】：

sed [OPTION]... {script-only-if-no-other-script} [input-file]...

【选项参数】：

参数	说明	简解
-n, --quiet, --silent	suppress automatic printing of pattern space	取消默认输出，只显示操作过的那一行
-e script, --expression=script	add the script to the commands to be executed	直接在命令列模式上进行sed的动作编辑
-f script-file, --file=script-file	add the contents of script-file to the commands to be executed	运行脚本内的动作
--follow-symlinks	follow symlinks when processing in place; hard links will still be broken
-i[SUFFIX], --in-place[=SUFFIX]	edit files in place (makes backup if extension supplied). The default operation mode is to break symbolic and hard links.This can be changed with --follow-symlinks and --copy	直接修改读取的文件内容
-c, --copy	use copy instead of rename when shuffling files in -i mode. While this will avoid breaking links (symbolic or hard), the resulting editing operation is not atomic. This is rarely the desired mode; --follow-symlinks is usually enough, and it is both faster and more secure.
-l N, --line-length=N	specify the desired line-wrap length for the ‘l’ command
--posix	disable all GNU extensions.
-r, --regexp-extended	use extended regular expressions in the script	在脚本中应用拓展的正则表达式
-s, --separate	consider files as separate rather than as a single continuous long stream
-u, --unbuffered	load minimal amounts of data from the input files and flush the output buffers more often

【示例】：

1、基本用法：仅列出 /etc/passwd 文件内的第 5-7 行

[root@oldboy ~]# nl /etc/passwd | sed -n '5,7p'

5 lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

6 sync:x:5:0:sync:/sbin:/bin/sync

7 shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

2、利用sed替换取IP地址

[root@oldboy ~]# ifconfig eth0

eth0 Link encap:Ethernet HWaddr 00:0C:29:9C:9A:32

inet addr:10.0.0.8 Bcast:10.0.0.255 Mask:255.255.255.0

inet6 addr: fe80::20c:29ff:fe9c:9a32/64 Scope:Link

UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

RX packets:641 errors:0 dropped:0 overruns:0 frame:0

TX packets:321 errors:0 dropped:0 overruns:0 carrier:0

collisions:0 txqueuelen:1000

RX bytes:56546 (55.2 KiB) TX bytes:40576 (39.6 KiB)

[root@oldboy ~]# /sbin/ifconfig eth0 | grep 'inet addr' | sed 's#^.*addr:##g' | sed 's#Bcast.*$##g'

10.0.0.8

3、直接修改文件内容

[root@oldboy ~]# cat test.txt

[root@oldboy ~]# sed -i 's#5#500#g' test.txt

[root@oldboy ~]# cat test.txt

500

【特别说明】：

动作说明： [n1[,n2]]function

n1, n2 ：不见得会存在，一般代表『选择进行动作的行数』，举例来说，如果我的动作是需要在 10 到 20 行之间进行的，则『 10,20[动作行为] 』

function：

a ：新增， a 的后面可以接字串，而这些字串会在新的一行出现(目前的下一行)～

c ：取代， c 的后面可以接字串，这些字串可以取代 n1,n2 之间的行！

d ：删除，因为是删除啊，所以 d 后面通常不接任何咚咚；

i ：插入， i 的后面可以接字串，而这些字串会在新的一行出现(目前的上一行)；

p ：打印，亦即将某个选择的数据印出。通常 p 会与参数 sed -n 一起运行～

s ：取代，可以直接进行取代的工作哩！通常这个 s 的动作可以搭配正则表达式！例如 1,20s#old#new#g 就是啦！

20. 【命令】：man

【功能说明】：

format and display the on-line manual pages ＃查看在线帮助手册

【语法格式】：

man [-acdDfFhkKtwW] [--path] [-m system] [-p string] [-C config_file]

[-M pathlist] [-P pager] [-B browser] [-H htmlpager] [-S sec-

tion_list] [section] name ...

【选项参数】：

参数	说明	简解

【示例】：

1、基本用法：查看在线帮助

[root@oldboy ~]# man ls

LS(1) User Commands LS(1)

NAME

ls - list directory contents

SYNOPSIS

ls [OPTION]... [FILE]...

以下省略

21. 【命令】：useradd

【功能说明】：

create a new user or update default new user information #创建新用户或更新默认新用户的信息

【语法格式】：

useradd [options] LOGIN

useradd -D

useradd -D [options]

【选项参数】：

参数	说明	简解
-c, --comment COMMENT	Any text string. It is generally a short description of the login, and is currently used as the field for the user's full name.	加上备注文字
-d, --home HOME_DIR	The new user will be created using HOME_DIR as the value for the user's login directory. The default is to append the LOGIN name to BASE_DIR and use that as the login directory name. The parent directory of HOME_DIR must exist otherwise the home directory cannot be created.	指定用户登入时的起始目录
-D, defaults	See below, the subsection "Changing the default values".	变更预设值
-e, --expiredate EXPIRE_DATE	The date on which the user account will be disabled. The date is specified in the format YYYY-MM-DD. If not specified, useradd will use the default expiry date specified by the EXPIRE variable in /etc/default/useradd, or an empty string (no expiry) by default.	指定账号的有效期限
-f, --inactive INACTIVE	The number of days after a password expires until the account is permanently disabled. A value of 0 disables the account as soon as the password has expired, and a value of -1 disables the feature. If not specified, useradd will use the default inactivity period specified by the INACTIVE variable in /etc/default/useradd, or -1 by default.	指定在密码过期后多少天即关闭该账号
-g, --gid GROUP	The group name or number of the user's initial login group. The group name must exist. A group number must refer to an already existing group.	指定用户所属的群组
-G, --groups GROUP1[,GROUP2,...[,GROUPN]]]	A list of supplementary groups which the user is also a member of. Each group is separated from the next by a comma, with no intervening whitespace. The groups are subject to the same restrictions as the group given with the -g option. The default is for the user to belong only to the initial group.	指定用户所属的附加群组
-m, --create-home	Create the user's home directory if it does not exist. The files and directories contained in the skeleton directory (which can be defined with the -k option) will be copied to the home directory.	自动建立用户的登入目录
-M	Do not create the user's home directory, even if the system wide setting from /etc/login.defs (CREATE_HOME) is set to yes.	不要自动建立用户的登入目录
-N, --no-user-group	Do not create a group with the same name as the user, but add the user to the group specified by the -g option or by the GROUP variable in /etc/default/useradd.	取消建立以用户名称为名的群组
-r, --system	Create a system account.	建立系统账号
-s, --shell SHELL	The name of the user's login shell. The default is to leave this field blank, which causes the system to select the default login shell specified by the SHELL variable in /etc/default/useradd, or an empty string by default.	指定用户登入后使用的shell
-u, --uid UID	The numerical value of the user's ID. This value must be unique, unless the -o option is used. The value must be non-negative. The default is to use the smallest ID value greater than or equal to UID_MIN and greater than every other user.	指定用户ID

【示例】：

1、基本用法：创建新用户

[root@oldboy ~]# useradd test

[root@oldboy ~]# cat /etc/passwd|tail -1

test:x:501:501::/home/test:/bin/bash

22. 【命令】：passwd

【功能说明】：

update user’s authentication tokens ＃为用户设置或修改密码

【语法格式】：

passwd [-k] [-l] [-u [-f]] [-d] [-e] [-n mindays] [-x

maxdays] [-w warndays] [-i inactivedays] [-S] [--stdin]

[username]

【选项参数】：

参数	说明	简解
-d	This is a quick way to delete a password for an account. It will set the named account password-less. Available to root only.	删除密码，仅有系统管理者才能使用
-k	The option -k, is used to indicate that the update should only be for expired authentication tokens (passwords); the user wishes to keep their non-expired tokens as before.	设置只有在密码过期失效后，方能更新
-l	This option is used to lock the specified account and it is available to root only. The locking is performed by rendering the encrypted password into an invalid string (by prefixing the encrypted string with an !).	锁住密码
-S	This will output a short information about the status of the password for a given account.Available to root user only.	列出密码的相关信息，仅有系统管理者才能使用
-u	This is the reverse of the -l option - it will unlock the account password by removing the !prefix. This option is available to root only. By default passwd will refuse to create a password-less account (it will not unlock an account that has only "!" as a password). The force option -f will override this protection.	解开已上锁的账号

【示例】：

1、基本用法：设置用户密码

[root@oldboy ~]# passwd oldboy

Changing password for user oldboy.

New password:

BAD PASSWORD: it is too simplistic/systematic

BAD PASSWORD: is too simple

Retype new password:

passwd: all authentication tokens updated successfully.

23. 【命令】：uname

【功能说明】：

print system information ＃打印系统信息

【语法格式】：

uname [OPTION]...

【选项参数】：

参数	说明	简解
-a, --all	print all information, in the following order, except omit -p and -i if unknown:	显示全部的信息
-s, --kernel-name	print the kernel name	显示操作系统类型
-n, --nodename	print the network node hostname	显示主机名
-r, --kernel-release	print the kernel release	显示核心版本号
-v, --kernel-version	print the kernel version	显示操作系统的版本
-m, --machine	print the machine hardware name	显示机器架构类型
-p, --processor	print the processor type or "unknown"
-i, --hardware-platform	print the hardware platform or "unknown"	显示硬件平台
-o, --operating-system	print the operating system	显示操作系统

【示例】：

1、基本用法：显示全部信息

[root@oldboy ~]# uname -a

Linux oldboy 2.6.32-573.el6.x86_64 #1 SMP Thu Jul 23 15:44:03 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

2、基本用法：显示主机名

[root@oldboy ~]# uname -n

oldboy

3、显示核心版本号

[root@oldboy ~]# uname -r

2.6.32-573.el6.x86_64

4、显示机器架构类型

[root@oldboy ~]# uname -m

x86_64

24. 【命令】：hostname

【功能说明】：

show or set the system’s host name ＃显示和设置主机名

【语法格式】：

hostname [-v] [-a] [--alias] [-d] [--domain] [-f]

[--fqdn] [-A] [--all-fqdns] [-i] [--ip-address] [-I]

[--all-ip-addresses] [--long] [-s] [--short] [-y] [--yp]

[--nis]

hostname [-v] [-F filename] [--file filename] [hostname]

【选项参数】：

参数	说明	简解
-v, --verbose	Be verbose and tell what’s going on.	详细信息模式
-a, --alias	Display the alias name of the host (if used)	显示主机别名
-d, --domain	Display the name of the DNS domain. Don’t use the command domainname to get the DNS domain name because it will show the NIS domain name and not the DNS domain name. Use dnsdomainname instead.	显示DNS域名
-f, --fqdn, --long	Display the FQDN (Fully Qualified Domain Name). A FQDN consists of a short host name and the DNS domain name. Unless you are using bind or NIS for host lookups you can change the FQDN and the DNS domain name (which is part of the FQDN) in the /etc/hosts file. See the warnings in section THE FQDN above, and avoid using this option; use hostname --all-fqdns instead	显示FQDN名称
-i, --ip-address	Display the IP address(es) of the host. Note that this works only if the host name can be resolved. Avoid using this option; use hostname --all-ip- addresses instead	显示主机的ip地址
-s, --short	Display the short host name. This is the host name cut at the first dot.	显示短主机名称，在第一个点处截断
-y, --yp, --nis	Display the NIS domain name. If a parameter is given (or --file name ) then root can also set a new NIS domain	显示NIS域名

【示例】：

1、基本用法：显示主机名

[root@oldboy ~]# hostname

oldboy

2、基本用法：修改主机名

[root@oldboy ~]# hostname oldgirl

[root@oldboy ~]# hostname

oldgirl

25. 【命令】：runlevel

【功能说明】：

output previous and current runlevel ＃查看系统运行状态

【语法格式】：

runlevel [OPTION]... [UTMP]

【选项参数】：

参数

说明

简解

--quiet

Does not output the current and previous run-level, nor does it output unknown in the case of error (but it will exit with an error code).

This may be used to test for the presence of a runlevel entry, or to check for errors reading from the file.

不显示当前运行状态

【示例】：

1、基本用法：查看系统运行状态

[root@oldboy ~]# runlevel

N 3

26. 【命令】：init

【功能说明】：

Upstart process management daemon ＃设置系统运行状态

【语法格式】：

init [OPTION]...

【选项参数】：

参数	说明	简解
-v, --verbose	Outputs verbose messages about job state changes and event emissions to the system console or log,useful for debugging boot.	显示详细信息
-q, --quiet	reduce output to errors only	只显示错误

【示例】：

1、基本用法：关机

[root@oldboy ~]# init 0

2、基本用法：重启

[root@oldboy ~]# init 6

27. 【命令】：shutdown

【功能说明】：

bring the system down ＃关机

【语法格式】：

shutdown [OPTION]... TIME [MESSAGE]

【选项参数】：

参数	说明	简解
-r	Requests that the system be rebooted after it has been brought down	重启系统
-h	Requests that the system be either halted or pow-ered off after it has been brought down, with the choice as to which left up to the system.	关机
-H	Requests that the system be halted after it has been brought down
-P	Requests that the system be powered off after it has been brought down.
-c	Cancels a running shutdown. TIME is not specified with this option, the first argument is MES-SAGE.	当执行“shutdown -h 11:50”指令时，只要按+键就可以中断关机的指令
-k	Only send out the warning messages and disable logins, do not actually bring the system down	只发送警告信息，不真关机

【示例】：

1、基本用法：立即关机

[root@oldboy ~]# shutdown -h now

2、指定12点关机

[root@oldboy ~]# shutdown -h 12:00

Broadcast message from root@oldboy

(/dev/pts/0) at 11:54 ...

The system is going down for halt in 6 minutes!

28. 【命令】：reboot

【功能说明】：

reboot the system ＃重启系统

【语法格式】：

reboot [OPTION]...

【选项参数】：

参数	说明	简解
-f, --force	Does not invoke shutdown(8) and instead performs the actual action you would expect from the name.	强制重新开机
-p, --poweroff	Instructs the halt command to instead behave as poweroff
-w, --wtmp-only	Does not call shutdown(8) or the reboot(2) system call and instead only writes the shutdown record to /var/log/wtmp	仅做测试，并不真正将系统重新开机，只会把重开机的数据写入/var/log目录下的wtmp记录文件。
--verbose	Outputs slightly more verbose messages when rebooting, useful for debugging problems with shutdown.
-n, --no-sync	don't sync before reboot or halt

【示例】：

1、基本用法：重启系统

[root@oldboy ~]# reboot

29. 【命令】：history

【功能说明】：

Display or manipulate the history list. ＃查看命令历史

【语法格式】：

history [-c] [-d offset] [n] or history -anrw [filename] or history -ps arg [arg...]

【选项参数】：

参数	说明	简解
-c	clear the history list by deleting all of the entries	清空当前历史命令
-d	offset delete the history entry at offset OFFSET
-a	append history lines from this session to the history file	将历史命令缓冲区中命令写入历史命令文件中
-n	read all history lines not already read from the history file
-r	read the history file and append the contents to the history list	将历史命令文件中的命令读入当前历史命令缓冲区
-w	write the current history to the history file and append them to the history list
-p	perform history expansion on each ARG and display the result without storing it in the history list
-s	append the ARGs to the history list as a single entry

【示例】：

1、基本用法：查看命令历史

[root@oldboy ~]# history

1 cd /usr/local/

2 cd ..

3 pwd

4 cd ../..

5 cd -

6 cd ~

7 cd /

8 ll

9 ls -la

......

30. 【命令】：dmesg

【功能说明】：

print or control the kernel ring buffer ＃查看系统故障信息

【语法格式】：

dmesg [-c] [-r] [-n level] [-s bufsize]

【选项参数】：

参数	说明	简解
-c	Clear the ring buffer contents after printing.	显示信息后，清除ring buffer中的内容
-r	Print the raw message buffer, i.e., don’t strip the log level prefixes.
-s bufsize	Use a buffer of size bufsize to query the kernel ring buffer. This is 16392 by default. (The default kernel syslog buffer size was 4096 at first, 8192 since 1.3.54, 16384 since 2.1.113.) If you have set the kernel buffer to be larger than the default then this option can be used to view the entire buffer	设置ring buffer大小，预设置为8196，刚好等于ring buffer的大小
-n level	Set the level at which logging of messages is done to the console. For example, -n 1 prevents all messages, except panic messages, from appear-ing on the console. All levels of messages are still written to /proc/kmsg, so syslogd(8) can still be used to control exactly where kernel messages appear. When the -n option is used,dmesg will not print or clear the kernel ring buffer	设置记录信息的层级

【示例】：

1、基本用法：查看信息

[root@oldboy ~]# dmesg

Initializing cgroup subsys cpuset

Initializing cgroup subsys cpu

Linux version 2.6.32-573.el6.x86_64 (mockbuild@c6b9.bsys.dev.centos.org) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-16) (GCC) ) #1 SMP Thu Jul 23 15:44:03 UTC 2015

Command line: ro root=UUID=8fc55236-ce36-4cc4-9924-202ed5142065 rd_NO_LUKS rd_NO_LVM LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet

31. 【命令】：ifup、ifdown

【功能说明】：

ifup - bring a network interface up ＃开启网卡

ifdown - take a network interface down ＃关闭网卡

【语法格式】：

ifup IFACE [boot]

ifdown IFACE

【选项参数】：

参数	说明	简解

【示例】：

1、基本用法：关闭、开启网卡

[root@oldboy ~]# ifdown eth0

[root@oldboy ~]# ifup eth0

Determining if ip address 10.0.0.8 is already in use for device eth0...

32. 【命令】：nl

【功能说明】：

number lines of files ＃显示文件行号

【语法格式】：

nl [OPTION]... [FILE]...

【选项参数】：

参数	说明	简解
-b, --body-numbering=STYLE	use STYLE for numbering body lines	指定行号指定的方式，主要有两种： -b a ：表示不论是否为空行，也同样列出行号(类似 cat -n)； -b t ：如果有空行，空的那一行不要列出行号(默认值)；
-d, --section-delimiter=CC	use CC for separating logical pages
-f, --footer-numbering=STYLE	use STYLE for numbering footer lines
-h, --header-numbering=STYLE	use STYLE for numbering header lines
-i, --line-increment=NUMBER	line number increment at each line
-l, --join-blank-lines=NUMBER	group of NUMBER empty lines counted as one
-n, --number-format=FORMAT	insert line numbers according to FORMAT	列出行号表示的方法，主要有三种： -n ln ：行号在萤幕的最左方显示； -n rn ：行号在自己栏位的最右方显示，且不加 0 ； -n rz ：行号在自己栏位的最右方显示，且加 0 ；
-p, --no-renumber	do not reset line numbers at logical pages	在逻辑定界符处不重新开始计算
-s, --number-separator=STRING	add STRING after (possible) line number
-v, --starting-line-number=NUMBER	first line number on each logical page
-w, --number-width=NUMBER	use NUMBER columns for line numbers	行号栏位的占用的位数

【示例】：

1、基本用法：显示行号（默认空行不显示）

[root@oldboy ~]# nl test.txt

1 10

2 14

3 99

4 8a1

5 69

2、显示行号（空行也显示）

[root@oldboy ~]# nl -b a test.txt

1 10

2 14

3 99

7 8a1

8 69

3、让行号前自动补上0，统一输出格式

[root@oldboy ~]# nl -b a -n rz test.txt

000001 10

000002 14

000003 99

000004

000005

000006

000007 8a1

000008 69

4、调整统一输出格式为三位数字

[root@oldboy ~]# nl -b a -n rz -w 3 test.txt

001 10

002 14

003 99

004

005

006

007 8a1

008 69

33. 【命令】：less

【功能说明】：

opposite of more ＃分屏查看文本（可回退）

【语法格式】：

less -?

less --help

less -V

less --version

less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]

[-b space] [-h lines] [-j line] [-k keyfile]

[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]

[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]

[-# shift] [+[+]cmd] [--] [filename]...

【选项参数】：

参数	说明	简解
-bn	Specifies the amount of buffer space less will use for each file, in units of kilobytes (1024 bytes). By default 64K of buffer space is used for each file (unless the file is a pipe; see the -B option). The -b option specifies instead that n kilobytes of buffer space should be used for each file. If n is -1, buffer space is unlimited; that is, the entire file can be read into memory.	设置缓冲区的大小
-e	Causes less to automatically exit the second time it reaches end-of-file. By default, the only way to exit less is via the "q" command.	当文件显示结束后，自动离开
-f	Forces non-regular files to be opened. (A non-regular file is a directory or a device special file.) Also suppresses the warning message when a binary file is opened. By default, less will refuse to open non-regular files. Note that some operating systems will not allow directories to be read, even if -f is set	强迫打开特殊文件，例如外围设备代号、目录和二进制文件
-g	Normally, less will highlight ALL strings which match the last search command. The -g option changes this behavior to highlight only the particular string which was found by the last search command. This can cause less to run somewhat faster than the default	只标志最后搜索的关键词
-i	Causes searches to ignore case; that is, uppercase and lowercase are considered identical. This option is ignored if any uppercase letters appear in the search pattern; in other words, if a pattern contains uppercase letters, then that search does not ignore case	忽略搜索时的大小写
-m	Causes less to prompt verbosely (like more), with the percent into the file. By default, less prompts with a colon	显示类似more命令的百分比
-N	Causes a line number to be displayed at the beginning of each line in the display.	显示每行的行号
-ofilename	Causes less to copy its input to the named file as it is being viewed. This applies only when the input file is a pipe, not an ordinary file. If the file already exists, less will ask for confirmation before overwriting it	将less 输出的内容在指定文件中保存起来
-Q	Causes totally "quiet" operation: the terminal bell is never rung.	不使用警告音
-s	Causes consecutive blank lines to be squeezed into a single blank line. This is useful when viewing nroff output	显示连续空行为一行
-S	Causes lines longer than the screen width to be chopped rather than folded. That is, the portion of a long line that does not fit in the screen width is not shown. The default is to fold long lines; that is, display the remainder on the next line	行过长时间将超出部分舍弃
-xn	Sets tab stops. If only one n is specified, tab stops are set at multiples of n. If multiple values separated by commas are specified, tab stops are set at those positions, and then continue with the same spacing as the last two. For example, -x9,17 will set tabs at positions 9, 17,25, 33, etc. The default for n is 8	将“tab”键显示为规定的数字空格

【示例】：

1、基本用法：查看文件

[root@oldboy ~]# less test.txt

8a1

【特别说明】

1.全屏导航

ctrl + F - 向前移动一屏

ctrl + B - 向后移动一屏

ctrl + D - 向前移动半屏

ctrl + U - 向后移动半屏

2.单行导航

j - 向前移动一行

k - 向后移动一行

3.其它导航

G - 移动到最后一行

g - 移动到第一行

q / ZZ - 退出 less 命令

4.其它有用的命令

v - 使用配置的编辑器编辑当前文件

h - 显示 less 的帮助文档

&pattern - 仅显示匹配模式的行，而不是整个文件

5.标记导航

当使用 less 查看大文件时，可以在任何一个位置作标记，可以通过命令导航到标有特定标记的文本位置：

ma - 使用 a 标记文本的当前位置

'a - 导航到标记 a 处

34. 【命令】：more

【功能说明】：

file perusal filter for crt viewing ＃分屏查看文件（不可回退）

【语法格式】：

more [-dlfpcsu] [-num] [+/pattern] [+linenum] [file ...]

【选项参数】：

参数	说明	简解
+num	Start at line number num	从笫n行开始显示
-num	This option specifies an integer which is the screen size (in lines)	定义屏幕大小为n行
+/pattern	The +/ option specifies a string that will be searched for before each file is displayed	在每个档案显示前搜寻该字串（pattern），然后从该字串前两行之后开始显示
-c	Do not scroll. Instead, paint each screen from the top, clearing the remainder of each line as it is displayed.	从顶部清屏，然后显示
-d	more will prompt the user with the message "[Press space to continue, ’q’ to quit.]" and will display"[Press ’h’ for instructions.]" instead of ringing the bell when an illegal key is pressed	提示“Press space to continue，’q’ to quit（按空格键继续，按q键退出）”，禁用响铃功能
-l	more usually treats ^L (form feed) as a special character, and will pause after any line that contains a form feed. The -l option will prevent this behavior.	忽略Ctrl+l（换页）字符
-p	Do not scroll. Instead, clear the whole screen and then display the text	通过清除窗口而不是滚屏来对文件进行换页，与-c选项相似
-s	Squeeze multiple blank lines into one.	把连续的多个空行显示为一行
-u	Suppress underlining	把文件内容中的下画线去掉

【示例】：

1、基本用法：查看文件

[root@oldboy ~]# more test.txt

8a1

【特别说明】

Enter 向下n行，需要定义。默认为1行

Ctrl+F 向下滚动一屏

空格键向下滚动一屏

Ctrl+B 返回上一屏

= 输出当前行的行号

：f 输出文件名和当前行的行号

V 调用vi编辑器

!命令调用Shell，并执行命令

q 退出more

35. 【命令】：wc

【功能说明】：

print newline, word, and byte counts for each file ＃打印行数、字数

【语法格式】：

wc [OPTION]... [FILE]...

wc [OPTION]... --files0-from=F

【选项参数】：

参数	说明	简解
-c, --bytes	print the byte counts	打印字节数
-m, --chars	print the character counts	打印字符数
-l, --lines	print the newline counts	打印行数
--files0-from=F	read input from the files specified by NUL-terminated names in file F; If F is - then read names from standard input
-L, --max-line-length	print the length of the longest line	打印最长行的长度
-w, --words	print the word counts	打印单词数

【示例】：

1、基本用法：打印行数、单词数、字节数及文件名

[root@oldboy ~]# wc test.txt

9 6 22 test.txt

2、只打印统计数字不打印文件名

[root@oldboy ~]# cat test.txt|wc -l

36. 【命令】：chkconfig

【功能说明】：

updates and queries runlevel information for system services ＃管理开机自启动程序

【语法格式】：

chkconfig [--list] [--type type][name]

chkconfig --add name

chkconfig --del name

chkconfig --override name

chkconfig [--level levels] [--type type] name<on|off|reset|resetpriorities>

chkconfig [--level levels] [--type type] name

【选项参数】：

参数	说明	简解
--level levels	Specifies the run levels an operation should pertain to. It is given as a string of numbers from 0 to 6. For example, --level 35 specifies run- levels 3 and 5	指定系统服务要在哪一个执行等级中开启或关毕
--add name	This option adds a new service for management by chkconfig. When a new service is added, chkconfig ensures that the service has either a start or a kill entry in every runlevel. If any run-level is missing such an entry, chkconfig creates the appropriate entry as specified by the default values in the init script. Note that default entries in LSB-delimited ’INIT INFO’ sections take precedence over the default runlevels in the initscript; if any Required-Start or Required-Stop entries are present, the start and stop priorities of the script will be adjusted to account for these dependencies	增加所指定的系统服务，让chkconfig指令得以管理它，并同时在系统启动的叙述文件内增加相关数据
--del name	The service is removed from chkconfig management,and any symbolic links in /etc/rc[0-6].d which pertain to it are removed.Note that future package installs for this service may run chkconfig --add, which will re-add such links. To disable a service, run chkconfig name off.	删除所指定的系统服务，不再由chkconfig指令管理，并同时在系统启动的叙述文件内删除相关数据
--list name	This option lists all of the services which chkconfig knows about, and whether they are stopped or started in each runlevel. If name is specified, information in only display about service name.	罗列所有服务在各执行等级上的开启、关闭情况

【示例】：

1、基本用法：查看所有服务在各执行等级上的开启、关闭情况

[root@oldboy ~]# chkconfig --list

abrt-ccpp 0:off 1:off 2:off 3:off 4:off 5:off 6:off

abrtd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

acpid 0:off 1:off 2:off 3:off 4:off 5:off 6:off

atd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

auditd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

blk-availability 0:off 1:on 2:off 3:off 4:off 5:off6:off

cpuspeed 0:off 1:on 2:off 3:off 4:off 5:off 6:off

crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off

haldaemon 0:off 1:off 2:off 3:off 4:off 5:off 6:off

......

2、基本用法：在指定执行等级上关闭（开启）一个服务

[root@oldboy ~]# chkconfig --level 2345 atd off

[root@oldboy ~]# chkconfig --list|grep "atd"

atd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

37. 【命令】：tar

【功能说明】：

manual page for tar 1.23 ＃打包命令

【语法格式】：

tar [OPTION...] [FILE]...

【选项参数】：

参数	说明	简解
-A	append tar files to an archive	新增压缩文件到已存在的压缩
-c	create a new archive	建立新的压缩文件
-d	find differences between archive and file system	记录文件的差别
-r	append files to the end of an archive	添加文件到已经压缩的文件结尾
-u	only append files newer than copy in archive	添加改变了和现有的文件到已经存在的压缩文件
-x	extract files from an archive	从压缩的文件中提取文件
-t	list the contents of an archive	显示压缩文件的内容
-z	filter the archive through gzip	支持gzip解压文件
-j	filter the archive through bzip2	支持bzip2解压文件
-v	verbosely list files processed	显示操作过程
-W	attempt to verify the archive after writing it	确认压缩文件的正确性
-C	change to directory DIR	切换到指定目录
-f	use archive file or device ARCHIVE	指定压缩文件

【示例】：

1、基本用法：打包文件zcvf

[root@oldboy ~]# tar zcvf data.tar.gz ./data

./data/

./data/d.txt

./data/oldboy.txt

./data/dir5/

./data/dir1/

./data/test.txt

./data/c.txt

./data/dir2/

./data/dir3/

./data/dir4/

./data/e.txt

[root@oldboy ~]# ls

anaconda-ks.cfg install.log oldboy test.txt

data install.log.syslog oldboy.tar.gz

data.tar.gz log2.txt oldboy.txt

2、基本用法：解包zxvf

[root@oldboy tmp]# tar zxvf data.tar.gz

./data/

./data/d.txt

./data/oldboy.txt

./data/dir5/

./data/dir1/

./data/test.txt

./data/c.txt

./data/dir2/

./data/dir3/

./data/dir4/

./data/e.txt

[root@oldboy tmp]# ls

data data.tar.gz file1.txt file2.txt oldboy test.txt

3、批量排除打包

[root@oldboy opt]# cat paichu.log
stu05
stu06
stu07
[root@oldboy opt]# tar zcvfX paichuX.tar.gz paichu.log ./test
./test/
./test/stu03
./test/stu01
./test/stu02
./test/stu09
./test/stu08
./test/stu10
./test/stu04
[root@oldboy opt]# tar tf paichuX.tar.gz
./test/
./test/stu03
./test/stu01
./test/stu02
./test/stu09
./test/stu08
./test/stu10
./test/stu04

38. 【命令】：cut

【功能说明】：

remove sections from each line of files ＃

【语法格式】：

cut OPTION... [FILE]...

【选项参数】：

参数	说明	简解
-b, --bytes=LIST	select only these bytes	以字节为单位进行分割
-c, --characters=LIST	select only these characters	以字符为单位进行分割
-d, --delimiter=DELIM	use DELIM instead of TAB for field delimiter	自定义分隔符，默认为制表符
-f, --fields=LIST	select only these fields; also print any line that contains no delimiter character, unless the -soption is specified	与-d一起使用，指定显示哪个区域
-n	with -b: don’t split multibyte characters	取消分割多字节字符仅和 -b 标志一起使用。如果字符的最后一个字节落在由 -b 标志的 List 参数指示的范围之内，该字符将被写出；否则，该字符将被排除。
--complement	complement the set of selected bytes, characters or fields	补足被选择的字节、字符或字段
-s, --only-delimited	do not print lines not containing delimiters	不打印不含分隔符的行
--output-delimiter=STRING	use STRING as the output delimiter the default is to use the input delimiter	指定分隔符打印样式

【示例】：

1、基本用法：以字节为单位取列

[root@oldboy ~]# cat oldboy.txt

inet addr:10.0.0.8 Bcast:10.0.0.255 Mask:255.255.255.0

[root@oldboy ~]# cut -b6-18 oldboy.txt

addr:10.0.0.8

2、基本用法：以字符为单位取列

[root@oldboy ~]# cat oldboy.txt

inet addr:10.0.0.8 Bcast:10.0.0.255 Mask:255.255.255.0

[root@oldboy ~]# cut -c6-18 oldboy.txt

addr:10.0.0.8

3、基本用法：以分隔符为单位取列

[root@oldboy ~]# cat /etc/passwd|head -5

root:x:0:0:root:/root:/bin/bash

bin:x:1:1:bin:/bin:/sbin/nologin

daemon:x:2:2:daemon:/sbin:/sbin/nologin

adm:x:3:4:adm:/var/adm:/sbin/nologin

lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin

[root@oldboy ~]# cat /etc/passwd|head -5|cut -d':' -f5

root

bin

daemon

adm

39. 【命令】：tr

【功能说明】：

translate or delete characters ＃转换或删除字符

【语法格式】：

tr [OPTION]... SET1 [SET2]

【选项参数】：

参数	说明	简解
-c, -C, --complement	use the complement of SET1	取代所有不属于第一字符集的字符
-d, --delete	delete characters in SET1, do not translate	删除所有属于第一字符集的字符
-s, --squeeze-repeats	replace each input sequence of a repeated character that is listed in SET1 with a single occurrence of that character	把连续重复的字符以单独一个字符表示
-t, --truncate-set1	first truncate SET1 to length of SET2	先删除第一字符集较第二字符集多出的字符

【示例】：

1、基本用法：替换字符

[root@oldboy ~]# echo abcdef|tr 'a-f' 'x-za-c'

xyzabc

2、删除字符

[root@oldboy ~]# echo abcdef|tr -d 'a-c'

def

3、连续重复的字符以单独一个字符表示

[root@oldboy ~]# echo aaabbbccc|tr -s 'abc'

abc

[root@oldboy ~]# echo aaabbbccc|tr -s 'a'

abbbccc

40. 【命令】：stat

【功能说明】：

display file or file system status ＃显示文件和文件系统状态（查看文件属性）

【语法格式】：

stat [OPTION]... FILE...

【选项参数】：

参数	说明	简解
-L, --dereference	follow links	如果是链接文件，则获取原文件信息
-Z, --context	print the SELinux security context	打印SELinux安全上下文信息
-f, --file-system	display file system status instead of file status	显示文件系统状态而非文件状态
-c --format=FORMAT	use the specified FORMAT instead of the default; output a newline after each use of FORMAT	自定义输出格式，结尾有换行
--printf=FORMAT	like --format, but interpret backslash escapes, and do not output a mandatory trailing newline. If you want a newline, include \n in FORMAT.	自定义输出格式，结尾无换行符，需手动添加
-t, --terse	print the information in terse form	以简洁方式输出信息

【示例】：

1、基本用法：查看文件信息

[root@oldboy ~]# stat test.txt

File: `test.txt'

Size: 22 Blocks: 8 IO Block: 4096 regular file

Device: 803h/2051d Inode: 11628 Links: 1

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

Access: 2016-03-19 16:08:55.616298620 +0800

Modify: 2016-03-19 16:08:44.504300222 +0800

Change: 2016-03-19 16:08:44.505300149 +0800

2、利用stat取文件权限属性

[root@oldboy ~]# stat test.txt

File: `test.txt'

Size: 22 Blocks: 8 IO Block: 4096 regular file

Device: 803h/2051d Inode: 11628 Links: 1

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

......

[root@oldboy ~]# stat -c %a test.txt

644

41. 【命令】：file

【功能说明】：

determine file type ＃显示文件类型

【语法格式】：

file [-bchikLNnprsvz0] [--apple] [--mime-encoding]

[--mime-type] [-e testname] [-F separator] [-f namefile]

[-m magicfiles] file ...

file -C [-m magicfiles]

file [--help]

【选项参数】：

参数	说明	简解
-b	Do not prepend filenames to output lines (brief mode)	列出文件辨识结果时，不显示文件名称。
-c	Cause a checking printout of the parsed form of the magic file. This is usually used in conjunction with the -m flag to debug a new magic file before installing it	详细显示指令执行过程，便于排错或分析程序执行的情形
-f	Read the names of the files to be examined from namefile (one per line) before the argument list.Either namefile or at least one filename argument must be present; to test the standard input, use ‘-’ as a filename argument.	列出文件中文件名的文件类型
-F	Use the specified string as the separator between the filename and the file result returned. Defaults to‘:’.	使用指定分隔符号替换输出文件名后的默认的“：”分隔符
-i	Causes the file command to output mime type strings rather than the more traditional human readable ones.Thus it may say ‘text/plain; charset=us-ascii’ rather than ‘ASCII text’. In order for this option to work,file changes the way it handles files recognized by the command itself (such as many of the text file types, directories etc), and makes use of an alternative ‘magic’ file. (See the FILES section, below)	输出mime类型的字符串
-L	option causes symlinks to be followed, as the like-named option in ls(1) (on systems that support symbolic links). This is the default if the environment variable POSIXLY_CORRECT is defined	查看对应软链接对应文件的文件类型
-z	Try to look inside compressed files.	尝试去解读压缩文件的内容

【示例】：

1、基本用法：显示文件类型

[root@oldboy ~]# file test.txt

test.txt: ASCII text

[root@oldboy ~]# file /data

/data: directory

42. 【命令】：last

【功能说明】：

show listing of last logged in users ＃查看用户登录信息

【语法格式】：

last [-R] [-num] [ -n num ] [-adFiowx] [ -f file ] [ -t

YYYYMMDDHHMMSS ] [name...] [tty...]

lastb [-R] [-num] [ -n num ] [ -f file ] [-adFiowx]

[name...] [tty...]

【选项参数】：

参数	说明	简解
-a	Display the hostname in the last column. Useful in combination with the next flag	将登录系统的的主机名称或IP地址，显示在最后一行
-d	For non-local logins, Linux stores not only the host name of the remote host but its IP number as well.This option translates the IP number back into a hostname	将IP地址转换成主机名称
-f	Specifies a file to search other than /var/log/wtmp	指定记录文件，默认是显示/var/log目录下的wtmp文件的记录，但/var/log目录下得btmp能显示的内容更丰富，可以显示远程登录，例如ssh登录，包括失败的登录请求
-i	This option is like -d in that it displays the IP number of the remote host, but it displays the IP number in numbers-and-dots notation.	-i显示特定ip登录的情况。跟踪用 -i显示特定ip登录的情况。跟踪用
-o	Read an old-type wtmp file (written by linux-libc5 applications).
-n	This is a count telling last how many lines to show.	-n <显示列数>或-<显示列数> 　设置列出名单的显示列数
-w	Display full user and domain names in the output
-R	Suppresses the display of the hostname field	不显示登入系统的主机名称或IP（省略 hostname 的栏位）
-t	Display the state of logins as of the specified time. This is useful, e.g., to determine easily who was logged in at a particular time -- specify that time with -t and look for "still logged in"	显示YYYYMMDDHHMMSS之前的信息
-x	Display the system shutdown entries and run level changes.	显示系统关闭、用户登录和退出的历史

【示例】：

1、基本用法：查看用户登录信息

[root@oldboy ~]# last

oldboy pts/0 10.0.0.1 Sun Mar 20 12:15 still logged in

reboot system boot 2.6.32-573.el6.x Sun Mar 20 12:15 - 15:08 (02:53)

oldboy pts/1 10.0.0.1 Sat Mar 19 15:36 - down (06:49)

root tty1 Sat Mar 19 15:35 - down (06:50)

2、显示最后登录系统的N条记录

[root@oldboy ~]# last -n 10

oldboy pts/0 10.0.0.1 Sun Mar 20 12:15 still logged in

reboot system boot 2.6.32-573.el6.x Sun Mar 20 12:15 - 15:25 (03:10)

oldboy pts/1 10.0.0.1 Sat Mar 19 15:36 - down (06:49)

root tty1 Sat Mar 19 15:35 - down (06:50)

oldboy pts/0 10.0.0.1 Sat Mar 19 10:28 - 15:52 (05:24)

reboot system boot 2.6.32-573.el6.x Sat Mar 19 10:28 - 22:25 (11:57)

root tty1 Sat Mar 19 10:27 - down (00:00)

oldboy pts/0 10.0.0.1 Sat Mar 19 10:20 - down (00:07)

oldboy pts/0 10.0.0.1 Sat Mar 19 10:19 - 10:20 (00:00)

reboot system boot 2.6.32-573.el6.x Sat Mar 19 10:19 - 10:27 (00:08)

wtmp begins Thu Mar 3 23:14:45 2016

3、将IP地址转换成主机名称

[root@oldboy ~]# last -n 5 -d

oldboy pts/0 localhost Sun Mar 20 12:15 still logged in

reboot system boot 0.0.0.0 Sun Mar 20 12:15 - 15:27 (03:11)

oldboy pts/1 localhost Sat Mar 19 15:36 - down (06:49)

root tty1 0.0.0.0 Sat Mar 19 15:35 - down (06:50)

oldboy pts/0 localhost Sat Mar 19 10:28 - 15:52 (05:24)

4、指定/var/log/btmp文件，查看登录系统的用户相关信息

[root@oldboy ~]# last -n 5 -f /var/log/btmp

btmp begins Thu Mar 3 23:14:22 2016

43. 【命令】：lastlog

【功能说明】：

reports the most recent login of all users or of a given user ＃查看最近登录的用户信息

【语法格式】：

lastlog [options]

【选项参数】：

参数	说明	简解
-b, --before DAYS	Print only lastlog records older than DAYS	显示指定天数前的登录信息
-h, --help	Display help message and exit.	显示帮助
-t, --time DAYS	Print the lastlog records more recent than DAYS	显示指定天数以来的登录信息
-u, --user LOGIN\|RANGE	Print the lastlog record of the specified user(s)	显示指定用户的最近登录信息

【示例】：

1、基本用法：显示最近登录的用户信息

[root@oldboy ~]# lastlog

Username Port From Latest

root tty1 Sat Mar 19 15:35:02 +0800 2016

bin **Never logged in**

daemon **Never logged in**

adm **Never logged in**

lp **Never logged in**

sync **Never logged in**

shutdown **Never logged in**

halt **Never logged in**

mail **Never logged in**

......

oldboy pts/0 10.0.0.1 Sun Mar 20 12:15:35 +0800 2016

test **Never logged in**

2、显示某一个用户最近登录信息

[root@oldboy ~]# lastlog -u oldboy

Username Port From Latest

oldboy pts/0 10.0.0.1 Sun Mar 20 12:15:35 +0800 2016

44. 【命令】：df

【功能说明】：

report file system disk space usage ＃查看系统磁盘空间的使用情况

【语法格式】：

df [OPTION]... [FILE]...

【选项参数】：

参数	说明	简解
-a	include dummy file systems	包含全部的文件系统
-B	use SIZE-byte blocks	以指定的区块大小来显示区块数目
-h	print sizes in human readable format (e.g., 1K 234M 2G)	以可读性较高的方式来显示信息
-H	likewise, but use powers of 1000 not 1024	与-h相同，但在计算时是以1000Bytes为换算单位而非1024 Bytes
-i	list inode information instead of block usage	显示inode的信息
-k	like --block-size=1K	指定区块大小为1024字节
-l	limit listing to local file systems	仅显示本地的文件系统
--no-sync	do not invoke sync before getting usage info (default)	在取得磁盘使用信息前，不要执行sync指令，此为预设值
-P	use the POSIX output format	使用POSIX的输出格式
--sync	invoke sync before getting usage info	在取得磁盘使用信息前，先执行sync指令
-t	limit listing to file systems of type TYPE	仅显示指定文件系统类型的磁盘信息
-T	print file system type	显示文件系统的类型
-x	limit listing to file systems not of type TYPE	不要显示指定文件系统类型的磁盘信息

【示例】：

1、基本用法：查看磁盘空间使用情况

[root@oldboy ~]# df

Filesystem 1K-blocks Used Available Use% Mounted on

/dev/sda3 7149156 1494028 5285312 23% /

tmpfs 243320 0 243320 0% /dev/shm

/dev/sda1 194241 40498 143503 23% /boot

[root@oldboy ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/sda3 6.9G 1.5G 5.1G 23% /

tmpfs 238M 0 238M 0% /dev/shm

/dev/sda1 190M 40M 141M 23% /boot

2、基本用法：查看inode的消耗情况

[root@oldboy ~]# df -hi

Filesystem Inodes IUsed IFree IUse% Mounted on

/dev/sda3 452K 55K 397K 13% /

tmpfs 60K 1 60K 1% /dev/shm

/dev/sda1 50K 39 50K 1% /boot

[root@oldboy ~]# df -i

Filesystem Inodes IUsed IFree IUse% Mounted on

/dev/sda3 462384 56221 406163 13% /

tmpfs 60830 1 60829 1% /dev/shm

/dev/sda1 51200 39 51161 1% /boot

45. 【命令】：dumpe2fs

【功能说明】：

dump ext2/ext3/ext4 filesystem information ＃查看文件系统内部信息（元数据）

【语法格式】：

dumpe2fs [ -bfhixV ] [ -o superblock=superblock ] [ -o blocksize=block-

size ] device

【选项参数】：

参数	说明	简解
-b	print the blocks which are reserved as bad in the filesystem	打印文件系统中预留的块信息
-o superblock=superblock	use the block superblock when examining the filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem	指定检查文件系统时使用的超级块
-o blocksize=blocksize	use blocks of blocksize bytes when examining the filesystem.This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem	检查文件系统时使用指定的块大小
-f	force dumpe2fs to display a filesystem even though it may have some filesystem feature flags which dumpe2fs may not understand(and which can cause some of dumpe2fs’s display to be suspect)
-h	only display the superblock information and not any of the block group descriptor detail information	仅显示超级块信息
-i	display the filesystem data from an image file created by e2image, using device as the pathname to the image file	从指定的文件系统映像文件中读取文件系统信息
-x	print the detailed group information block numbers in hexadecimal format	以16进制格式打印信息块成员
-V	print the version number of dumpe2fs and exit.

【示例】：

1、基本用法：查看文件系统内部信息

[root@oldboy ~]# dumpe2fs /dev/sda1

dumpe2fs 1.41.12 (17-May-2010)

Filesystem volume name: <none>

Last mounted on: /boot

Filesystem UUID: 3e368f7e-0775-4c00-afba-f8880d916366

Filesystem magic number: 0xEF53

Filesystem revision #: 1 (dynamic)

Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super huge_file uninit_bg dir_nlink extra_isize

Filesystem flags: signed_directory_hash

Default mount options: user_xattr acl

......

Group 0: (Blocks 1-8192) [ITABLE_ZEROED]

Checksum 0x303a, unused inodes 2009

Primary superblock at 1, Group descriptors at 2-2

Reserved GDT blocks at 3-258

Block bitmap at 259 (+258), Inode bitmap at 275 (+274)

Inode table at 291-546 (+290)

3785 free blocks, 2009 free inodes, 6 directories, 2009 unused inodes

Free blocks: 4408-8192

Free inodes: 40-2048

Group 1: (Blocks 8193-16384) [INODE_UNINIT, ITABLE_ZEROED]

......

46. 【命令】：tree

【功能说明】：

list contents of directories in a tree-like format ＃以树的形式罗列目录内容

【语法格式】：

tree [-adfghilnopqrstuvxACDFNS] [-L level [-R]] [-H baseHREF] [-T title] [-o

filename] [--nolinks] [-P pattern] [-I pattern] [--inodes] [--device]

[--noreport] [--dirsfirst] [--version] [--help] [--filelimit #] [directory

...]

【选项参数】：

参数	说明	简解
-a	All files are printed. By default tree does not print hidden files(those beginning with a dot ‘.’). In no event does tree print the file system constructs ‘.’ (current directory) and ‘..’ (previous directory)	显示所有文件和目录
-A	Turn on ANSI line graphics hack when printing the indentation lines	使用ASNI绘图字符显示树状图而非以ASCII字符组合
-C	Turn colorization on always, using built-in color defaults if the LS_COLORS environment variable is not set. Useful to colorize output to a pipe	在文件和目录清单加上色彩，便于区分各种类型
-d	List directories only	只罗列目录
-D	Print the date of the last modification time for the file listed	列出文件或目录的更改时间
-L	Max display depth of the directory tree	罗列的层次深度
-f	Prints the full path prefix for each file	在每个文件或目录之前，显示完整的相对路径名称
-F	Append a ‘/’ for directories, a ‘=’ for socket files, a ‘*’ for executable files and a ‘\|’ for FIFO’s, as per ls -F	在执行文件，目录，Socket，符号连接，管道名称名称，各自加上"*","/","=","@","\|"号
-g	Print the group name, or GID # if no group name is available, of the file.	列出文件或目录的所属群组名称，没有对应的名称时，则显示群组识别码
-i	Makes tree not print the indentation lines, useful when used in conjunction with the -f option	不以阶梯状列出文件或目录名称
-I	Do not list those files that match the wild-card pattern	不显示符合范本样式的文件或目录名称
-l	Follows symbolic links if they point to directories, as if they were directories. Symbolic links that will result in recursion are avoided when detected	如遇到性质为符号连接的目录，直接列出该连接所指向的原始目录
-n	Turn colorization off always, over-ridden by the -C option	不在文件和目录清单加上色彩
-N	Print non-printable characters as is instead of the default caret notation	直接列出文件和目录名称，包括控制字符
-p	Print the file type and permissions for each file (as per ls -l)	列出权限标示
-P	List only those files that match the wild-card pattern. Note: you must use the -a option to also consider those files beginning with a dot ‘.’ for matching. Valid wildcard operators are ‘*’ (any zero or more characters), ‘?’ (any single character), ‘[...]’ (any single character listed between brackets (optional - (dash) for character range may be used: ex: [A-Z]), and ‘[^...]’ (any single character not listed in brackets) and ‘\|’ separates alternate patterns	只显示符合范本样式的文件或目录名称
-q	Print non-printable characters in filenames as question marks instead of the default caret notation	用"?"号取代控制字符，列出文件和目录名称
-s	Print the size of each file in bytes along with the name	列出文件或目录大小
-t	Sort the output by last modification time instead of alphabetically	用文件和目录的更改时间排序
-u	Print the username, or UID # if no username is available, of the file	列出文件或目录的拥有者名称，没有对应的名称时，则显示用户识别码
-x	Stay on the current file-system only. Ala find -xdev	将范围局限在现行的文件系统中，若指定目录下的某些子目录，其存放于另一个文件系统上，则将该子目录予以排除在寻找范围外

【示例】：

1、基本用法：以树形罗列目录

[root@oldboy ~]# tree oldboy

oldboy

├── ext

│ └── oldboy

├── jeacen

├── oldboy

├── test

├── wodi.gz

├── xiaodong

├── xiaofan

├── xingfujie

└── yingsui.gz

2、只罗列目录

[root@oldboy ~]# tree -d

├── data

│ ├── dir1

│ ├── dir2

│ ├── dir3

│ ├── dir4

│ └── dir5

└── oldboy

├── ext

├── test

├── xiaodong

├── xiaofan

└── xingfujie

3、只罗列目录，显示深度为1层

[root@oldboy ~]# tree -Ld 1

├── data

└── oldboy

4、显示完整的相对路径

[root@oldboy ~]# tree -f data

data

├── data/c.txt

├── data/dir1

├── data/dir2

├── data/dir3

├── data/dir4

├── data/dir5

├── data/d.txt

├── data/e.txt

├── data/oldboy.txt

└── data/test.txt

5、不以阶梯状形式显示

[root@oldboy ~]# tree -i data

data

c.txt

dir1

dir2

dir3

dir4

dir5

d.txt

e.txt

oldboy.txt

test.txt

6、为显示内容添加提示符

[root@oldboy ~]# tree -F oldboy

oldboy

├── ext/

│ └── oldboy

├── jeacen

├── oldboy

├── test/

├── wodi.gz

├── xiaodong/

├── xiaofan/

├── xingfujie/

└── yingsui.gz

47. 【命令】：id

【功能说明】：

print real and effective user and group IDs ＃显示用户ID及组ID

【语法格式】：

id [OPTION]... [USERNAME]

【选项参数】：

参数	说明	简解
-a	ignore, for compatibility with other versions
-Z	print only the security context of the current user
-g	print only the effective group ID	显示用户所属群组的ID
-G	print all group IDs	显示用户所有群组的ID
-n	print a name instead of a number, for -ugG	显示用户所属群组的名称
-r	print the real ID instead of the effective ID, with -ugG	显示实际ID
-u	print only the effective user ID	显示用户ID

【示例】：

1、基本用法：显示用户ID及组ID

[oldboy@oldboy ~]$ id oldboy

2、显示用户ID

[oldboy@oldboy ~]$ id -u oldboy

500

48. 【命令】：ln

【功能说明】：

make links between files ＃创建链接

【语法格式】：

ln [OPTION]... [-T] TARGET LINK_NAME (1st form)

ln [OPTION]... TARGET (2nd form)

ln [OPTION]... TARGET... DIRECTORY (3rd form)

ln [OPTION]... -t DIRECTORY TARGET... (4th form)

【选项参数】：

参数	说明	简解
-f	remove existing destination files	链接时先将与dist同档案名的档案删除
-d	allow the superuser to attempt to hard link directories (note: will probably fail due to system restrictions, even for the superuser)	允许系统管理者硬链接自己的目录
-i	prompt whether to remove destinations	在删除与dist同名的档案时先进行询问
-n	treat destination that is a symlink to a directory as if it were a normal file	在进行软链接时，将dist视为一般的档案
-s	make symbolic links instead of hard links	创建软链接
-v	print name of each linked file	在链接之前显示其档案名
-b	like --backup but does not accept an argument	将在链接时会被覆写或删除的档案进行备份
-S	override the usual backup suffix	将备份的档案都加上SUFFIX的字尾

【示例】：

1、基本用法：创建文件硬链接

[root@oldboy ~]# ln oldboy.txt oldboy_hard_link

[root@oldboy ~]# ls

anaconda-ks.cfg install.log log2.txt oldboy_hard_link oldboy.txt

data install.log.syslog oldboy oldboy.tar.gz test.txt

2、基本用法：创建文件软链接

[root@oldboy ~]# ln -s oldboy.txt oldboy_soft_link

[root@oldboy ~]# ls

anaconda-ks.cfg install.log log2.txt oldboy_hard_link oldboy.tar.gz test.txt

data install.log.syslog oldboy oldboy_soft_link oldboy.txt

49. 【命令】：du

【功能说明】：

estimate file space usage ＃查看文件和目录大小

【语法格式】：

du [OPTION]... [FILE]...

du [OPTION]... --files0-from=F

【选项参数】：

参数	说明	简解
-a	write counts for all files, not just directories	显示目录中所有文件大小
-b	equivalent to ‘--apparent-size --block-size=1’	显示目录或文件大小时，以byte为单位
-c	produce a grand total	显示一个大小总和
-k	like --block-size=1K	以KB为单位输出
-m	like --block-size=1M	以MB为单位输出
-s	display only a total for each argument	仅显示总计，只列出最后加总的值
-h	print sizes in human readable format (e.g., 1K 234M 2G)	人类可读
-x	skip directories on different file systems	以一开始处理时的文件系统为准，若遇上其它不同的文件系统目录则略过
-L	dereference all symbolic links	显示选项中所指定符号链接的源文件大小
-S	do not include size of subdirectories	显示个别目录的大小时，并不含其子目录的大小
-X	exclude files that match any pattern in FILE
--exclude=PATTERN	exclude files that match PATTERN	略过指定的目录或文件
-D	dereference only symlinks that are listed on the command line	显示指定符号链接的源文件大小
-H	equivalent to --dereference-args (-D)	与-h参数相同，但是是以1000为换算单位
-l	count sizes many times if hard linked	重复计算硬链接的文件

【示例】：

1、基本用法：显示目录或文件所占空间

[root@oldboy ~]# du

4 ./oldboy/xiaofan

8 ./oldboy/ext

4 ./oldboy/xingfujie

4 ./oldboy/xiaodong

4 ./oldboy/test

40 ./oldboy

4 ./data/dir5

4 ./data/dir1

4 ./data/dir2

4 ./data/dir3

4 ./data/dir4

28 ./data

172 .

2、显示指定文件所占空间

[root@oldboy ~]# du oldboy.txt

4 oldboy.txt

3、显示指定目录所占空间

[root@oldboy ~]# du oldboy

4 oldboy/xiaofan

8 oldboy/ext

4 oldboy/xingfujie

4 oldboy/xiaodong

4 oldboy/test

40 oldboy

4、以易读模式显示

[root@oldboy ~]# du -h

4.0K ./oldboy/xiaofan

8.0K ./oldboy/ext

4.0K ./oldboy/xingfujie

4.0K ./oldboy/xiaodong

4.0K ./oldboy/test

40K ./oldboy

4.0K ./data/dir5

4.0K ./data/dir1

4.0K ./data/dir2

4.0K ./data/dir3

4.0K ./data/dir4

28K ./data

172K .

50. 【命令】：which

【功能说明】：

shows the full path of (shell) commands ＃从PATH变量所在路径查找二进制命令

【语法格式】：

which [options] [--] programname [...]

【选项参数】：

参数	说明	简解

【示例】：

1、基本用法：查找命令

[root@oldboy ~]# which cat

/bin/cat

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