Similar to the for command, while is also the command for loop operations. The command next to while is evaluated. If it is successful or 0, then the commands inside do and done are executed.
The purpose of a loop is to test a certain condition or expression and execute a given command while the condition is true (the while loop) or until the condition becomes true (the until loop):
while condition do commands done |
until condition do commands done |
The following is the while_01.sh script in which we read a file and display its content:
#!/bin/bash file=/etc/resolv.conf while IFS= read -r line # IFS : inter field separator do # echo line is stored in $line echo $line done < "$file"
Let's test the ...