Shell Exit Codes

Exit Codes

Conventions

• 0 = Success: Non-Zero indicates an issue
• 1 = Failure
• 2 = Failure (due to a usage problem)
• 3-63 = Program-Specific Exit Codes
• 64-79 = BSD SysExits (https://man.openbsd.org/sysexits.3)
• 80-119 = Custom

Many shells use exit codes 126-128 to signal specific error status:

• 126 is for the shell and indicates command found but is not executable.
• 127 is for the shell and indicate command not found.
• 128 is for invalid argument to exit.

Many shells use exit codes above 128 in their $?; Representation of the exit status to encode the signal number of a process being killed.

• 128+n means fatal error signal “n”
• Example: 130 means terminated by CTRL+C (Because CTRL+C is signal 2)
• Example: 137 means terminated by kill -9 (because 128 + 9 = 137)

Finally, the highest exit code:

• 255 Exit status out of range (exit takes integer args 0-255)