Exit codes in bash indicate the previous command’s termination status. 0 indicates that command completion was successful while 1 indicates that command execution failed.
We can check the exit code generated by last command by using $?
$ echo $?
It’s not only 1 that indicates unsuccessful completion, anything greater than 1 is a sign of command failure. Standard error code are listed here:
|1||Unsuccessful execution catchall|
|2||Incorrect use of shell builtin|
|126||Command can not execute|
|127||Command not Found|
|128||Incorrect exit code argument|
|128 + num||Fatal error signal “num”|
|130||Script killed with CTRL + C|
|255+||Exit code is out of range|
Note: Exit code is an integer value between 0 and/or 255.