Bash读取txt文件并存储在数组中

I'm writing my first Bash script, I have some experience with C and C# so I think the logic of the program is correct, it's just the syntax is so complicated because apparently there are many different ways to write the same thing!

我正在编写我的第一个Bash脚本，我对C和C＃有一些经验，所以我认为程序的逻辑是正确的，只是语法是如此复杂，因为显然有很多不同的方法来编写同样的东西！

Here is the script, it simply checks if the argument (string) is contained in a certain file. If so it stores each line of the file in an array and writes an item of the array in a file. I'm sure there must be easier ways to achieve that but I want to do some practice with bash loops

这是脚本，它只是检查参数（字符串）是否包含在某个文件中。如果是这样，它将文件的每一行存储在一个数组中，并将该数组的项写入文件中。我确信必须有更简单的方法来实现这一点，但我想用bash循环做一些练习

#!/bin/bash

NOME=$1
c=0

#IF NAME IS FOUND IN THE PHONEBOOK THEN STORE EACH LINE OF THE FILE INTO ARRAY
#ONCE THE ARRAY IS DONE GET THE INDEX OF MATCHING NAME AND RETURN ARRAY[INDEX+1]

if grep "$NOME" /root/phonebook.txt ; then
        echo "CREATING ARRAY"
        while read line
        do
                myArray[$c]=$line # store line
                c=$(expr $c + 1) # increase counter by 1
        done < /root/phonebook.txt

else
        echo "Name not found"
fi

c=0
for i in myArray;
        do
              if   myArray[$i]="$NOME" ;  then
                 echo ${myArray[i+1]} >> /root/numbertocall.txt
              fi

done

This code returns the only the second item of myArray (myArray[2]) or the second line of the file, why?

这段代码只返回myArray的第二项（myArray [2]）或文件的第二行，为什么？

2 个解决方案

#1

The first part (where you build the array) looks ok, but the second part has a couple of serious errors:

第一部分（构建数组的位置）看起来不错，但第二部分有几个严重的错误：

for i in myArray; -- this executes the loop once, with $i set to "myArray". In this case, you want $i to iterate over the indexes of myArray, so you need to use

我在myArray中; - 这会执行循环一次，$ i设置为“myArray”。在这种情况下，您希望$ i迭代myArray的索引，因此您需要使用
```
for i in "${!myArray[@]}"
```
or

要么
```
for ((i=0; i<${#a[@]}; i++))
```
(although I generally prefer the first, since it'll work with noncontiguous and associative arrays).

（虽然我通常更喜欢第一个，因为它适用于非连续和关联数组）。

Also, you don't need the ; unless do is on the same line (in shell, ; is mostly equivalent to a line break so having a semicolon at the end of a line is redundant).

另外，你不需要;除非do在同一行上（在shell中，;大部分相当于换行符，因此在行尾有一个分号是多余的）。
if myArray[$i]="$NOME" ; then -- the if statement takes a command, and will therefore treat myArray[$i]="$NOME" as an assignment command, which is not at all what you wanted. In order to compare strings, you could use the test command or its synonym [

如果myArray [$ i] =“$ NOME”;然后 - if语句接受一个命令，因此将myArray [$ i] =“$ NOME”视为一个赋值命令，这根本不是你想要的。为了比较字符串，您可以使用test命令或其同义词[
```
if [ "${myArray[i]}" = "$NOME" ]; then
```
or a bash conditional expression

或者bash条件表达式
```
if [[ "${myArray[i]}" = "$NOME" ]]; then
```
The two are very similar, but the conditional expression has much cleaner syntax (e.g. in a test command, > redirects output, while \> is a string comparison; in [[ ]] a plain > is a comparison).

两者非常相似，但条件表达式具有更清晰的语法（例如，在测试命令中，>重定向输出，而\>是字符串比较;在[[]]中，普通>是比较）。

In either case, you need to use an appropriate $ expression for myArray, or it'll be interpreted as a literal. On the other hand, you don't need a $ before the i in "${myArray[i]}" because it's in a numeric expression context and therefore will be expanded automatically.

在任何一种情况下，您都需要为myArray使用适当的$表达式，否则它将被解释为文字。另一方面，在“$ {myArray [i]}”中你不需要$之前的$，因为它在数值表达式上下文中，因此会自动扩展。

Finally, note that the spaces between elements are absolutely required -- in shell, spaces are very important delimiters, not just there for readability like they usually are in c.

最后，请注意元素之间的空格是绝对必需的 - 在shell中，空格是非常重要的分隔符，而不仅仅是它们通常在c中的可读性。

#2

1.-This is what you wrote with small adjustments

1.-这是你用小调整写的

#!/bin/bash

NOME=$1

#IF NAME IS FOUND IN THE PHONE-BOOK **THEN** READ THE PHONE BOOK LINES INTO AN ARRAY VARIABLE
#ONCE THE ARRAY IS COMPLETED, GET THE INDEX OF MATCHING LINE AND RETURN ARRAY[INDEX+1]

c=0
if grep "$NOME" /root/phonebook.txt ; then

       echo "CREATING ARRAY...."
       IFS= while read -r line    #IFS= in case you want to preserve leading and trailing spaces
       do
             myArray[c]=$line     # put line in the array
             c=$((c+1))           # increase counter by 1
       done < /root/phonebook.txt


       for i in ${!myArray[@]}; do
             if  myArray[i]="$NOME" ;  then
                 echo ${myArray[i+1]} >> /root/numbertocall.txt
             fi
       done


else
       echo "Name not found"
fi

2.-But you can also read the array and stop looping like this:

2.-但您也可以读取数组并停止循环：

#!/bin/bash

NOME=$1

c=0
if grep "$NOME" /root/phonebook.txt ; then

       echo "CREATING ARRAY...."
       readarray myArray < /root/phonebook.txt


       for i in ${!myArray[@]}; do
             if  myArray[i]="$NOME" ;  then
                 echo ${myArray[i+1]} >> /root/numbertocall.txt
                 break            # stop looping
             fi
       done


else
       echo "Name not found"
fi
exit 0

3.- The following improves things. Supposing a)$NAME matches the whole line that contains it and b)there's always one line after a $NOME found, this will work; if not (if $NOME can be the last line in the phone-book), then you need to do small adjustments.

3.-以下改进了一些事情。假设a）$ NAME匹配包含它的整行，b）在找到$ NOME之后总是有一行，这将起作用;如果没有（如果$ NOME可以是电话簿中的最后一行），那么你需要做一些小的调整。

!/bin/bash
PHONEBOOK="/root/phonebook.txt"
NUMBERTOCALL="/root/numbertocall.txt"
NOME="$1"
myline=""

myline=$(grep -A1 "$NOME" "$PHONEBOOK" | sed '1d')

if [ -z "$myline" ]; then 
      echo "Name not found :-("

else
      echo -n "$NOME FOUND.... "
      echo "$myline" >> "$NUMBERTOCALL"
      echo  " .... AND SAVED! :-)"

fi
exit 0

#1