shell exit code numbers, meanings, examples and comments

shell_exit_codes.sh

#!/bin/sh

header='"Exit_Code_Number","Meaning","Example","Comments"'
"1","Catchall for general errors","let 'var1 = 1/0'","Miscellaneous errors, such as 'divide by zero' and other impermissible operations"
"2","Misuse of shell builtins (according to Bash documentation)","empty_function() {}","Missing keyword or command, or permission problem (and diff return code on a failed binary file comparison)"
"126","Command invoked cannot execute","/dev/null","Permission problem or command is not an executable"
"127","command not found","illegal_command","Possible problem with $PATH or a typo"
"128","Invalid argument to exit","exit 3.14159","exit takes only integer args in the range 0 - 255 (see first footnote)"
"128+n","Fatal error signal 'n'","kill -9","$PPID of script $? returns 137 (128 + 9)"
"130","Script terminated by Control-C","Ctl-C","Control-C is fatal error signal 2, (130 = 128 + 2, see above)"
"255*","Exit status out of range","exit -1","exit takes only integer args in the range 0 - 255"