I tried:
我试着:
sed -i 's/\n+/\n/' file
but it's not working.
但这不是工作。
I still want single line breaks.
我仍然想要单线插播。
Input:
输入:
abc
def
ghi
jkl
Desired output:
期望的输出:
abc
def
ghi
jkl
6 个解决方案
#1
3
Sed isn't very good at tasks that examine multiple lines programmatically. Here is the closest I could get:
Sed并不擅长以编程方式检查多行。这是我能得到的最接近的结果:
$ sed '/^$/{n;/^$/d}' file
abc
def
ghi
jkl
The logic of this: if you find a blank line, look at the next line. If that next line is also blank, delete that next line.
这样做的逻辑是:如果你找到一条空行，看看下一行。如果下一行也是空的，那么删除下一行。
This doesn't gobble up all of the lines in the end because it assumes that there was an intentional extra pair and reduced the two \n\ns down to two \ns.
这并没有把所有的线都吃光，因为它假设有一个有意的额外的一对，并把两个\n减少到两个\n。
To do it in basic awk:
在基本awk中完成:
$ awk 'NF > 0 {blank=0} NF == 0 {blank++} blank < 2' file
abc
def
ghi
jkl
This uses a variable called blank, which is zero when the number of fields (NF) is nonzero and increments when they are zero (a blank line). Awk's default action, printing, is performed when the number of consecutive blank lines is less than two.
它使用一个名为blank的变量，当字段数(NF)为非零时为零，当字段数为零时为增量(空行)。Awk的默认操作是打印，当连续空行数小于2时执行。
#2
1
perl -00 -pe 1 filename
That splits the input file into "paragraphs" separated by 2 or more newlines, and then prints the paragraphs separated by a single blank line:
将输入文件分成两行或两行以上的“段落”，然后打印用一行空行分隔的段落:
perl -00 -pe 1 <<END
abc
def
ghi
jkl
END
abc
def
ghi
jkl
#3
1
Using awk (gnu or BSD) you can do:
使用awk (gnu或BSD)，您可以:
awk -v RS= -v ORS='\n\n' '1' file
abc
def
ghi
jkl
Also using perl:
也使用perl:
perl -pe '$/=""; s/(\n)+/$1$1/' file
abc
def
ghi
jkl
#4
0
This might work for you (GNU sed):
这可能对你有用(GNU sed):
sed '/^$/{:a;N;s/\n$//;ta}' file
This replaces multiple blank lines by a single blank line.
这将用一个空行替换多个空行。
However if you want to place a blank line after each non-blank line then:
但是，如果您想在每个非空行之后放置一个空行，则:
sed '/^$/d;G' file
Which deletes all blank lines and only appends a single blank line to a non-blank line.
它删除所有的空行，只将一个空行附加到一个非空行。
#5
-1
Why not just get rid of all your blank lines, then add a single blank line after each line? For an input file tmp as you specified,
为什么不去掉所有的空行，然后在每一行后面添加一个空行呢?对于您指定的输入文件tmp，
sed '/^$/d' tmp|sed '0~1 a\ '
abc
def
ghi
jkl
If white space (spaces and tabs) counts as a "blank" line for you, then use sed '/^\s*$/d' tmp|sed '0~1 a\ ' instead.
如果空白(空格和制表符)计数作为一个“空白”线,然后使用sed ' / ^ \ s *美元/ d ' tmp | sed“0 ~ 1 \”。
Note that these solutions do leave a trailing blank line at the end, as I wasn't sure if this was desired. Easily removed.
请注意，这些解决方案在最后会留下一个尾随的空行，因为我不确定是否需要这样做。轻松地删除。
#6
-1
This gives you what you want using solely sed :
这为您提供了使用单独sed所需的内容:
sed '/^$/d' txt | sed -e $'s/$/\\\n/'
The first sed command removes all empty lines, denoted as "^$".
第一个sed命令删除所有空行,指示为“^ $”。
The second sed command inserts one newline character at the end of each line.
第二个sed命令在每一行的末尾插入一个换行字符。
#1
3
Sed isn't very good at tasks that examine multiple lines programmatically. Here is the closest I could get:
Sed并不擅长以编程方式检查多行。这是我能得到的最接近的结果:
$ sed '/^$/{n;/^$/d}' file
abc
def
ghi
jkl
The logic of this: if you find a blank line, look at the next line. If that next line is also blank, delete that next line.
这样做的逻辑是:如果你找到一条空行，看看下一行。如果下一行也是空的，那么删除下一行。
This doesn't gobble up all of the lines in the end because it assumes that there was an intentional extra pair and reduced the two \n\ns down to two \ns.
这并没有把所有的线都吃光，因为它假设有一个有意的额外的一对，并把两个\n减少到两个\n。
To do it in basic awk:
在基本awk中完成:
$ awk 'NF > 0 {blank=0} NF == 0 {blank++} blank < 2' file
abc
def
ghi
jkl
This uses a variable called blank, which is zero when the number of fields (NF) is nonzero and increments when they are zero (a blank line). Awk's default action, printing, is performed when the number of consecutive blank lines is less than two.
它使用一个名为blank的变量，当字段数(NF)为非零时为零，当字段数为零时为增量(空行)。Awk的默认操作是打印，当连续空行数小于2时执行。
#2
1
perl -00 -pe 1 filename
That splits the input file into "paragraphs" separated by 2 or more newlines, and then prints the paragraphs separated by a single blank line:
将输入文件分成两行或两行以上的“段落”，然后打印用一行空行分隔的段落:
perl -00 -pe 1 <<END
abc
def
ghi
jkl
END
abc
def
ghi
jkl
#3
1
Using awk (gnu or BSD) you can do:
使用awk (gnu或BSD)，您可以:
awk -v RS= -v ORS='\n\n' '1' file
abc
def
ghi
jkl
Also using perl:
也使用perl:
perl -pe '$/=""; s/(\n)+/$1$1/' file
abc
def
ghi
jkl
#4
0
This might work for you (GNU sed):
这可能对你有用(GNU sed):
sed '/^$/{:a;N;s/\n$//;ta}' file
This replaces multiple blank lines by a single blank line.
这将用一个空行替换多个空行。
However if you want to place a blank line after each non-blank line then:
但是，如果您想在每个非空行之后放置一个空行，则:
sed '/^$/d;G' file
Which deletes all blank lines and only appends a single blank line to a non-blank line.
它删除所有的空行，只将一个空行附加到一个非空行。
#5
-1
Why not just get rid of all your blank lines, then add a single blank line after each line? For an input file tmp as you specified,
为什么不去掉所有的空行，然后在每一行后面添加一个空行呢?对于您指定的输入文件tmp，
sed '/^$/d' tmp|sed '0~1 a\ '
abc
def
ghi
jkl
If white space (spaces and tabs) counts as a "blank" line for you, then use sed '/^\s*$/d' tmp|sed '0~1 a\ ' instead.
如果空白(空格和制表符)计数作为一个“空白”线,然后使用sed ' / ^ \ s *美元/ d ' tmp | sed“0 ~ 1 \”。
Note that these solutions do leave a trailing blank line at the end, as I wasn't sure if this was desired. Easily removed.
请注意，这些解决方案在最后会留下一个尾随的空行，因为我不确定是否需要这样做。轻松地删除。
#6
-1
This gives you what you want using solely sed :
这为您提供了使用单独sed所需的内容:
sed '/^$/d' txt | sed -e $'s/$/\\\n/'
The first sed command removes all empty lines, denoted as "^$".
第一个sed命令删除所有空行,指示为“^ $”。
The second sed command inserts one newline character at the end of each line.
第二个sed命令在每一行的末尾插入一个换行字符。