342 lines
12 KiB
Bash
342 lines
12 KiB
Bash
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# bash-preexec.sh -- Bash support for ZSH-like 'preexec' and 'precmd' functions.
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# https://github.com/rcaloras/bash-preexec
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#
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#
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# 'preexec' functions are executed before each interactive command is
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# executed, with the interactive command as its argument. The 'precmd'
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# function is executed before each prompt is displayed.
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#
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# Author: Ryan Caloras (ryan@bashhub.com)
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# Forked from Original Author: Glyph Lefkowitz
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#
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# V0.4.1
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#
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# General Usage:
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#
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# 1. Source this file at the end of your bash profile so as not to interfere
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# with anything else that's using PROMPT_COMMAND.
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#
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# 2. Add any precmd or preexec functions by appending them to their arrays:
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# e.g.
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# precmd_functions+=(my_precmd_function)
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# precmd_functions+=(some_other_precmd_function)
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#
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# preexec_functions+=(my_preexec_function)
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#
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# 3. Consider changing anything using the DEBUG trap or PROMPT_COMMAND
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# to use preexec and precmd instead. Preexisting usages will be
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# preserved, but doing so manually may be less surprising.
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#
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# Note: This module requires two Bash features which you must not otherwise be
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# using: the "DEBUG" trap, and the "PROMPT_COMMAND" variable. If you override
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# either of these after bash-preexec has been installed it will most likely break.
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# Make sure this is bash that's running and return otherwise.
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if [[ -z "${BASH_VERSION:-}" ]]; then
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return 1;
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fi
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# Avoid duplicate inclusion
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if [[ "${__bp_imported:-}" == "defined" ]]; then
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return 0
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fi
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__bp_imported="defined"
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# Should be available to each precmd and preexec
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# functions, should they want it. $? and $_ are available as $? and $_, but
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# $PIPESTATUS is available only in a copy, $BP_PIPESTATUS.
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# TODO: Figure out how to restore PIPESTATUS before each precmd or preexec
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# function.
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__bp_last_ret_value="$?"
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BP_PIPESTATUS=("${PIPESTATUS[@]}")
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__bp_last_argument_prev_command="$_"
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__bp_inside_precmd=0
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__bp_inside_preexec=0
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# Initial PROMPT_COMMAND string that is removed from PROMPT_COMMAND post __bp_install
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__bp_install_string=$'__bp_trap_string="$(trap -p DEBUG)"\ntrap - DEBUG\n__bp_install'
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# Fails if any of the given variables are readonly
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# Reference https://stackoverflow.com/a/4441178
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__bp_require_not_readonly() {
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local var
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for var; do
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if ! ( unset "$var" 2> /dev/null ); then
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echo "bash-preexec requires write access to ${var}" >&2
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return 1
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fi
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done
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}
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# Remove ignorespace and or replace ignoreboth from HISTCONTROL
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# so we can accurately invoke preexec with a command from our
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# history even if it starts with a space.
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__bp_adjust_histcontrol() {
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local histcontrol
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histcontrol="${HISTCONTROL//ignorespace}"
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# Replace ignoreboth with ignoredups
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if [[ "$histcontrol" == *"ignoreboth"* ]]; then
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histcontrol="ignoredups:${histcontrol//ignoreboth}"
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fi;
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export HISTCONTROL="$histcontrol"
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}
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# This variable describes whether we are currently in "interactive mode";
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# i.e. whether this shell has just executed a prompt and is waiting for user
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# input. It documents whether the current command invoked by the trace hook is
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# run interactively by the user; it's set immediately after the prompt hook,
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# and unset as soon as the trace hook is run.
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__bp_preexec_interactive_mode=""
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# Trims leading and trailing whitespace from $2 and writes it to the variable
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# name passed as $1
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__bp_trim_whitespace() {
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local var=${1:?} text=${2:-}
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text="${text#"${text%%[![:space:]]*}"}" # remove leading whitespace characters
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text="${text%"${text##*[![:space:]]}"}" # remove trailing whitespace characters
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printf -v "$var" '%s' "$text"
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}
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# Trims whitespace and removes any leading or trailing semicolons from $2 and
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# writes the resulting string to the variable name passed as $1. Used for
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# manipulating substrings in PROMPT_COMMAND
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__bp_sanitize_string() {
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local var=${1:?} text=${2:-} sanitized
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__bp_trim_whitespace sanitized "$text"
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sanitized=${sanitized%;}
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sanitized=${sanitized#;}
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__bp_trim_whitespace sanitized "$sanitized"
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printf -v "$var" '%s' "$sanitized"
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}
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# This function is installed as part of the PROMPT_COMMAND;
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# It sets a variable to indicate that the prompt was just displayed,
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# to allow the DEBUG trap to know that the next command is likely interactive.
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__bp_interactive_mode() {
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__bp_preexec_interactive_mode="on";
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}
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# This function is installed as part of the PROMPT_COMMAND.
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# It will invoke any functions defined in the precmd_functions array.
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__bp_precmd_invoke_cmd() {
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# Save the returned value from our last command, and from each process in
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# its pipeline. Note: this MUST be the first thing done in this function.
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__bp_last_ret_value="$?" BP_PIPESTATUS=("${PIPESTATUS[@]}")
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# Don't invoke precmds if we are inside an execution of an "original
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# prompt command" by another precmd execution loop. This avoids infinite
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# recursion.
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if (( __bp_inside_precmd > 0 )); then
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return
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fi
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local __bp_inside_precmd=1
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# Invoke every function defined in our function array.
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local precmd_function
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for precmd_function in "${precmd_functions[@]}"; do
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# Only execute this function if it actually exists.
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# Test existence of functions with: declare -[Ff]
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if type -t "$precmd_function" 1>/dev/null; then
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__bp_set_ret_value "$__bp_last_ret_value" "$__bp_last_argument_prev_command"
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# Quote our function invocation to prevent issues with IFS
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"$precmd_function"
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fi
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done
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}
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# Sets a return value in $?. We may want to get access to the $? variable in our
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# precmd functions. This is available for instance in zsh. We can simulate it in bash
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# by setting the value here.
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__bp_set_ret_value() {
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return ${1:-}
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}
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__bp_in_prompt_command() {
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local prompt_command_array
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IFS=$'\n;' read -rd '' -a prompt_command_array <<< "$PROMPT_COMMAND"
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local trimmed_arg
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__bp_trim_whitespace trimmed_arg "${1:-}"
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local command trimmed_command
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for command in "${prompt_command_array[@]:-}"; do
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__bp_trim_whitespace trimmed_command "$command"
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if [[ "$trimmed_command" == "$trimmed_arg" ]]; then
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return 0
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fi
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done
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return 1
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}
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# This function is installed as the DEBUG trap. It is invoked before each
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# interactive prompt display. Its purpose is to inspect the current
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# environment to attempt to detect if the current command is being invoked
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# interactively, and invoke 'preexec' if so.
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__bp_preexec_invoke_exec() {
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# Save the contents of $_ so that it can be restored later on.
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# https://stackoverflow.com/questions/40944532/bash-preserve-in-a-debug-trap#40944702
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__bp_last_argument_prev_command="${1:-}"
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# Don't invoke preexecs if we are inside of another preexec.
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if (( __bp_inside_preexec > 0 )); then
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return
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fi
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local __bp_inside_preexec=1
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# Checks if the file descriptor is not standard out (i.e. '1')
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# __bp_delay_install checks if we're in test. Needed for bats to run.
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# Prevents preexec from being invoked for functions in PS1
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if [[ ! -t 1 && -z "${__bp_delay_install:-}" ]]; then
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return
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fi
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if [[ -n "${COMP_LINE:-}" ]]; then
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# We're in the middle of a completer. This obviously can't be
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# an interactively issued command.
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return
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fi
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if [[ -z "${__bp_preexec_interactive_mode:-}" ]]; then
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# We're doing something related to displaying the prompt. Let the
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# prompt set the title instead of me.
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return
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else
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# If we're in a subshell, then the prompt won't be re-displayed to put
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# us back into interactive mode, so let's not set the variable back.
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# In other words, if you have a subshell like
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# (sleep 1; sleep 2)
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# You want to see the 'sleep 2' as a set_command_title as well.
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if [[ 0 -eq "${BASH_SUBSHELL:-}" ]]; then
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__bp_preexec_interactive_mode=""
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fi
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fi
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if __bp_in_prompt_command "${BASH_COMMAND:-}"; then
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# If we're executing something inside our prompt_command then we don't
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# want to call preexec. Bash prior to 3.1 can't detect this at all :/
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__bp_preexec_interactive_mode=""
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return
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fi
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local this_command
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this_command=$(
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export LC_ALL=C
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HISTTIMEFORMAT= builtin history 1 | sed '1 s/^ *[0-9][0-9]*[* ] //'
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)
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# Sanity check to make sure we have something to invoke our function with.
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if [[ -z "$this_command" ]]; then
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return
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fi
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# Invoke every function defined in our function array.
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local preexec_function
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local preexec_function_ret_value
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local preexec_ret_value=0
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for preexec_function in "${preexec_functions[@]:-}"; do
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# Only execute each function if it actually exists.
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# Test existence of function with: declare -[fF]
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if type -t "$preexec_function" 1>/dev/null; then
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__bp_set_ret_value ${__bp_last_ret_value:-}
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# Quote our function invocation to prevent issues with IFS
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"$preexec_function" "$this_command"
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preexec_function_ret_value="$?"
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if [[ "$preexec_function_ret_value" != 0 ]]; then
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preexec_ret_value="$preexec_function_ret_value"
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fi
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fi
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done
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# Restore the last argument of the last executed command, and set the return
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# value of the DEBUG trap to be the return code of the last preexec function
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# to return an error.
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# If `extdebug` is enabled a non-zero return value from any preexec function
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# will cause the user's command not to execute.
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# Run `shopt -s extdebug` to enable
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__bp_set_ret_value "$preexec_ret_value" "$__bp_last_argument_prev_command"
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}
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__bp_install() {
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# Exit if we already have this installed.
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if [[ "${PROMPT_COMMAND:-}" == *"__bp_precmd_invoke_cmd"* ]]; then
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return 1;
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fi
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trap '__bp_preexec_invoke_exec "$_"' DEBUG
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# Preserve any prior DEBUG trap as a preexec function
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local prior_trap=$(sed "s/[^']*'\(.*\)'[^']*/\1/" <<<"${__bp_trap_string:-}")
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unset __bp_trap_string
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if [[ -n "$prior_trap" ]]; then
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eval '__bp_original_debug_trap() {
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'"$prior_trap"'
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}'
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preexec_functions+=(__bp_original_debug_trap)
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fi
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# Adjust our HISTCONTROL Variable if needed.
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__bp_adjust_histcontrol
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# Issue #25. Setting debug trap for subshells causes sessions to exit for
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# backgrounded subshell commands (e.g. (pwd)& ). Believe this is a bug in Bash.
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#
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# Disabling this by default. It can be enabled by setting this variable.
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if [[ -n "${__bp_enable_subshells:-}" ]]; then
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# Set so debug trap will work be invoked in subshells.
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set -o functrace > /dev/null 2>&1
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shopt -s extdebug > /dev/null 2>&1
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fi;
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local existing_prompt_command
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# Remove setting our trap install string and sanitize the existing prompt command string
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existing_prompt_command="${PROMPT_COMMAND//$__bp_install_string[;$'\n']}" # Edge case of appending to PROMPT_COMMAND
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existing_prompt_command="${existing_prompt_command//$__bp_install_string}"
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__bp_sanitize_string existing_prompt_command "$existing_prompt_command"
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# Install our hooks in PROMPT_COMMAND to allow our trap to know when we've
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# actually entered something.
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PROMPT_COMMAND=$'__bp_precmd_invoke_cmd\n'
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if [[ -n "$existing_prompt_command" ]]; then
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PROMPT_COMMAND+=${existing_prompt_command}$'\n'
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fi;
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PROMPT_COMMAND+='__bp_interactive_mode'
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# Add two functions to our arrays for convenience
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# of definition.
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precmd_functions+=(precmd)
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preexec_functions+=(preexec)
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# Invoke our two functions manually that were added to $PROMPT_COMMAND
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__bp_precmd_invoke_cmd
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__bp_interactive_mode
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}
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# Sets an installation string as part of our PROMPT_COMMAND to install
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# after our session has started. This allows bash-preexec to be included
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# at any point in our bash profile.
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__bp_install_after_session_init() {
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# bash-preexec needs to modify these variables in order to work correctly
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# if it can't, just stop the installation
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__bp_require_not_readonly PROMPT_COMMAND HISTCONTROL HISTTIMEFORMAT || return
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local sanitized_prompt_command
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__bp_sanitize_string sanitized_prompt_command "$PROMPT_COMMAND"
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if [[ -n "$sanitized_prompt_command" ]]; then
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PROMPT_COMMAND=${sanitized_prompt_command}$'\n'
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fi;
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PROMPT_COMMAND+=${__bp_install_string}
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}
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# Run our install so long as we're not delaying it.
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if [[ -z "${__bp_delay_install:-}" ]]; then
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__bp_install_after_session_init
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fi;
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