L_trap¶

Trap and other related functions.

The most important and overused function is here L_print_traceback. It print the full traceback with the source code locations. This is one of the features I missed in Bash a lot. Where did the error happen?

When . L_lib.sh is sourced without -n argument, it executes L_trap_err_init. If set -e is set and trap ERR is empty, it will execute the function L_trap_err_enable to set the trap on ERR to print the traceback if a command fails.

You can also trap 'L_trap_err $?' EXIT to print the error code and the last command that failed. This is useful for debugging.

It is all built around L_print_traceback function which prints the whole bash traceback in a python-like format style.

Then there are L_trap_push and L_trap_pop functions to push and pop another code block with a newline to the trap handler. This is a work in progress, as it would be amazing to handle $? correctly.

trap ¶

L_print_traceback ¶

Prints traceback

:

  Example traceback:
  Traceback from pid 3973390 (most recent call last):
    File ./bin/L_lib.sh, line 2921, in main()
  2921 >> _L_lib_main "$@"
    File ./bin/L_lib.sh, line 2912, in _L_lib_main()
  2912 >>                 "test") _L_lib_run_tests "$@"; ;;
    File ./bin/L_lib.sh, line 2793, in _L_lib_run_tests()
  2793 >>                 "$_L_test"
    File ./bin/L_lib.sh, line 891, in _L_test_other()
  891  >>                 L_unittest_eq "$max" 4
    File ./bin/L_lib.sh, line 1412, in L_unittest_eq()
  1412 >>                 _L_unittest_showdiff "$1" "$2"
    File ./bin/L_lib.sh, line 1391, in _L_unittest_showdiff()
  1391 >>                 sdiff <(cat <<<"$1") - <<<"$2"

Arguments:

[$1] int stack offset to start from (default: 0)
[$2] int number of lines to show around the line (default: 2)

L_trap_err_small ¶

Callback to be exectued on ERR trap that prints just the caller.

Example

  trap 'L_trap_err_small' ERR

L_trap_err ¶

description Callback to be exectued on ERR trap that prints a traceback and exits.

Example

   trap 'L_trap_err $?' ERR
   trap 'L_trap_err $?' EXIT

Argument: $1 int exit code

L_trap_err_enable ¶

Enable ERR trap with L_trap_err as callback

set -eEo functrace and register trap 'L_trap_err $?' ERR.

Example

 L_trap_err_enable

L_trap_err_disable ¶

Disable ERR trap

Example

  L_trap_err_disable

L_trap_err_init ¶

If set -e is set and ERR trap is not set, enable ERR trap with L_trap_err as callback

Example

   L_trap_err_init

$L_TRAP_RETURN_RESTORE_SHOPT ¶

Create a return trap that restores all shopt options.

Example

  func() {
     eval "$L_TRAP_RETURN_RESTORE_SHOPT"
     shopt -s extglob
     # stuff with extglob
  }

L_trap_to_number ¶

Convert trap name to number

Option: -v <var> var

Argument: $1 trap name or trap number

L_trap_to_number_v ¶

L_trap_to_name ¶

convert trap number to trap name

Example

L_trap_to_name -v var 0 && L_assert '' test "$var" = EXIT

Option: -v <var> var

Argument: $1 signal name or signal number

L_trap_to_name_v ¶

L_trap_get ¶

Get the current value of trap

Example

  trap 'echo hi' EXIT
  L_trap_get -v var EXIT
  L_assert '' test "$var" = 'echo hi'

Option: -v <var> var

Argument: $1 signal name or number

L_trap_get_v ¶

L_trap_push ¶

Suffix a newline and the command to the trap value

Arguments:

$1 str command to execute
$2 str signal to handle

L_trap_pop ¶

remove a command from trap up until the last newline

Argument: $1 str signal to handle

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