reading a file using shell script

Question

I have a text file named sqlfile , with the following content:

a.sql
b.sql
c.sql
d.sql

What I want is that to store them in variables and then print using for loop. But here I get only d.sql in the output of the script.

The script:

#!/bin/bash

while read line
do
files=`echo $line`
done < /home/abdul_old/Desktop/My_Shell_Script/sqlfile

for file in $files
        do
                echo $file
        done

Answer 1

A variable can only hold one element, what you want is an array

#!/bin/bash

while read line
do
  files+=( "$line" )
done < /home/abdul_old/Desktop/My_Shell_Script/sqlfile

for file in "${files[@]}"
do
  echo "$file"
done

Answer 2

while read line
do files="$files $line"
done < /home/abdul_old/Desktop/My_Shell_Script/sqlfile

or

files=$(</home/abdul_old/Desktop/My_Shell_Script/sqlfile)

or

files=$(cat /home/abdul_old/Desktop/My_Shell_Script/sqlfile)

You're doing way too much work in your loop.

The middle alternative works with bash ; the other two work with most shells. Prefer $(...) to back-quotes.

This code assumes there are no spaces in file names to mess things up. If you do use blanks in file names, you have to work marginally harder - see the array-based solution by SiegeX

Answer 3

使用read很好，但你必须首先设置IFS环境变量，否则从每行中删除前导和尾随空格： 在读取时保留前导空格>>在bash中逐行写入文件 。

Answer 4

All you have to do is:

readarray myData < sqlfile

This will put file lines into an array called myData
Now you can access any of these lines like this:

printf "%s\n" "${myData[0]}" #outputs first line
printf "%s\n" "${myData[2]}" #outputs third line

And you can iterate over it:

for curLine in "${myData[@]}"; do
    echo "$curLine"
done

Note that these lines would contain \\n character as well. To remove trailing newlines you can use -t flag like this:

readarray -t myData < sqlfile

readarray is a synonym to mapfile . You can read about it in man bash

Answer 5

I think you need to make the "files" as array. otherwise, as soon as the while finishes, "files" stores the latest "line". try:

files=( "${files[@]}" $line )

Answer 6

That's right, you assifn last value to "files"

You must use for instance += instead of =

#!/bin/bash

while read line
do
files+=`echo " $line"`
done < /home/abdul_old/Desktop/My_Shell_Script/sqlfile

for file in $files
        do
                echo $file
        done