Working with the do while loop
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 (while loop) or until the condition becomes true (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 it's 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 program:
$ chmod +x while_01.sh $ ./while_01.sh
The following will be the output after executing the preceding commands:
nameserver 192.168.168.2 search localdomain
In the following script while_02.sh, we are printing number 1–10 on the screen using the while...
