Skip to content

Instantly share code, notes, and snippets.

@docwhat
Last active April 6, 2022 02:52
Show Gist options
  • Save docwhat/5889193 to your computer and use it in GitHub Desktop.
Save docwhat/5889193 to your computer and use it in GitHub Desktop.
A template showing how to do bash tracebacks. This makes using `set -eu` much more comfortable.
#!/bin/bash
#
# Tracebacks in bash
# https://docwhat.org/tracebacks-in-bash/
#
# Just take the code between the "cut here" lines
# and put it in your own program.
#
# Written by Christian Höltje
# Donated to the public domain in 2013
#--------->8---------cut here---------8<---------
set -eu
trap _exit_trap EXIT
trap _err_trap ERR
_showed_traceback=f
function _exit_trap() {
local _ec="$?"
if [[ $_ec != 0 && ${_showed_traceback} != t ]]; then
traceback 1
fi
}
function _err_trap() {
local _ec="$?"
local _cmd="${BASH_COMMAND:-unknown}"
traceback 1
_showed_traceback=t
echo "The command ${_cmd} exited with exit code ${_ec}." 1>&2
}
function traceback() {
# Hide the traceback() call.
local -i start=$((${1:-0} + 1))
local -i end=${#BASH_SOURCE[@]}
local -i i=0
local -i j=0
echo "Traceback (last called is first):" 1>&2
for ((i = start; i < end; i++)); do
j=$((i - 1))
local function="${FUNCNAME[$i]}"
local file="${BASH_SOURCE[$i]}"
local line="${BASH_LINENO[$j]}"
echo " ${function}() in ${file}:${line}" 1>&2
done
}
#--------->8---------cut here---------8<---------
########
## Demos
function bomb() {
trap _err_trap ERR
local limit=${1:-5}
echo -n " ${limit}"
if [ "${limit}" -le 0 ]; then
echo " BOOM"
return 10
else
bomb $((limit - 1))
fi
}
function stack() {
stack_1
}
function stack_1() {
stack_2
}
function stack_2() {
stack_3
}
function stack_3() {
no_such_function
}
#######
## Main
case "${1:-}" in
stack)
stack
;;
bomb)
echo -n "Counting down..."
bomb
;;
badvar)
echo "This shouldn't be shown because ${bad_variable} isn't set"
;;
false)
false
;;
true)
true
;;
*)
echo "Usage: $0 [bomb|badvar|true|false|stack]"
;;
esac
# EOF
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment