Can you explains and provide us "Bourne Shell Exit Status Code" examples?
Each UNIX command returns a status when it terminates. If it is not successful, it returns a code which tells the shell to print an error message. You can use the
exit command to leave a shell program with a certain exit status.
Typical Values Of Exit Status
- 0 Success.
- 1 A built-in command failure.
- 2 A syntax error has occurred.
- 3 Signal received that is not trapped.
How Do I Print Exit Status?
Type the command:
To print its exit status type the command:
$ echo $?
Try a few more examples:
To store exit status of the last executed command to a shell variable called status, enter:
You can use exit status with test command or if command too.
#!/bin/sh user="$1" if grep "$user" /etc/passwd; then echo "$user has an account" else echo "$user doesn't have an account" fi
Run it as follows:
The grep command is used as condition but it can actually be any command. If it returns a zero exit status, the condition is true; otherwise, it is false. In this example, the while loop executes given commands as long as condition is true. Again, condition can be any command, and is true if the command exits with a zero exit status.
while condition; do commands done
Here is another simple example:
#!/bin/sh x=0 while [ $x != 3 ] do let x=x+1 echo $x done
Here is another example:
#!/bin/shRun it as follows:
while [ -r "$1" ]
cat $1 >> output
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