HowTo : Read a file Line By Line
If you need to read each line from a file and perform some action with it, then you can use 'while' loop.
while read line; do [COMMAND]; done < [INPUT_FILE]
Single Line Example
The next command will print the file 'file.txt' line by line, adding "This is a line :" at the beginning of each line.
while read line; do echo "$line"; done < file.txt
The next script will print file line by line :
#!/bin/bash FILE=$1 while read line; do echo "This is a line : $line" done < $FILE
Save and execute the script :
This is a line : root:x:0:0:root:/root:/bin/bash
This is a line : bin:x:1:1:bin:/bin:/sbin/nologin
This is a line : daemon:x:2:2:daemon:/sbin:/sbin/nologin