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64 lines
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64 lines
15 KiB
4 years ago
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<title>relearn_bash_preexec</title>
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<body># __PUBLISH__<br># bash-preexec.sh -- Bash support for ZSH-like 'preexec' and 'precmd' functions.<br># <a href="https://github.com/rcaloras/bash-preexec" rel="noreferrer noopener">https://github.com/rcaloras/bash-preexec</a>
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<br>#<br>#<br># 'preexec' functions are executed before each interactive command is<br># executed, with the interactive command as its argument. The 'precmd'<br># function is executed before each prompt is displayed.<br>#<br># Author: Ryan Caloras (ryan@bashhub.com)<br># Forked from Original Author: Glyph Lefkowitz<br>#<br># V0.3.7<br>#<br>
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<br># General Usage:<br>#<br># 1. Source this file at the end of your bash profile so as not to interfere<br># with anything else that's using PROMPT_COMMAND.<br>#<br># 2. Add any precmd or preexec functions by appending them to their arrays:<br># e.g.<br># precmd_functions+=(my_precmd_function)<br># precmd_functions+=(some_other_precmd_function)<br>#<br># preexec_functions+=(my_preexec_function)<br>#<br># 3. Consider changing anything using the DEBUG trap or PROMPT_COMMAND<br># to use preexec and precmd instead. Preexisting usages will be<br># preserved, but doing so manually may be less surprising.<br>#<br># Note: This module requires two Bash features which you must not otherwise be<br># using: the "DEBUG" trap, and the "PROMPT_COMMAND" variable. If you override<br># either of these after bash-preexec has been installed it will most likely break.<br>
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<br># Avoid duplicate inclusion<br>if [[ "${__bp_imported:-}" == "defined" ]]; then<br> return 0<br>fi<br>__bp_imported="defined"<br>
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<br># Should be available to each precmd and preexec<br># functions, should they want it. $? and $_ are available as $? and $_, but<br># $PIPESTATUS is available only in a copy, $BP_PIPESTATUS.<br># TODO: Figure out how to restore PIPESTATUS before each precmd or preexec<br># function.<br>__bp_last_ret_value="$?"<br>BP_PIPESTATUS=("${PIPESTATUS[@]}")<br>__bp_last_argument_prev_command="$_"<br>
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<br>__bp_inside_precmd=0<br>__bp_inside_preexec=0<br>
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<br># Fails if any of the given variables are readonly<br># Reference <a href="https://stackoverflow.com/a/4441178" rel="noreferrer noopener">https://stackoverflow.com/a/4441178</a>
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<br>__bp_require_not_readonly() {<br> for var; do<br> if ! ( unset "$var" 2> /dev/null ); then<br> echo "bash-preexec requires write access to ${var}" >&2<br> return 1<br> fi<br> done<br>}<br>
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<br># Remove ignorespace and or replace ignoreboth from HISTCONTROL<br># so we can accurately invoke preexec with a command from our<br># history even if it starts with a space.<br>__bp_adjust_histcontrol() {<br> local histcontrol<br> histcontrol="${HISTCONTROL//ignorespace}"<br> # Replace ignoreboth with ignoredups<br> if [[ "$histcontrol" == *"ignoreboth"* ]]; then<br> histcontrol="ignoredups:${histcontrol//ignoreboth}"<br> fi;<br> export HISTCONTROL="$histcontrol"<br>}<br>
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<br># This variable describes whether we are currently in "interactive mode";<br># i.e. whether this shell has just executed a prompt and is waiting for user<br># input. It documents whether the current command invoked by the trace hook is<br># run interactively by the user; it's set immediately after the prompt hook,<br># and unset as soon as the trace hook is run.<br>__bp_preexec_interactive_mode=""<br>
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<br>__bp_trim_whitespace() {<br> local var=$@<br> var="${var#"${var%%[![:space:]]*}"}" # remove leading whitespace characters<br> var="${var%"${var##*[![:space:]]}"}" # remove trailing whitespace characters<br> echo -n "$var"<br>}<br>
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<br># This function is installed as part of the PROMPT_COMMAND;<br># It sets a variable to indicate that the prompt was just displayed,<br># to allow the DEBUG trap to know that the next command is likely interactive.<br>__bp_interactive_mode() {<br> __bp_preexec_interactive_mode="on";<br>}<br>
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<br>
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<br># This function is installed as part of the PROMPT_COMMAND.<br># It will invoke any functions defined in the precmd_functions array.<br>__bp_precmd_invoke_cmd() {<br> # Save the returned value from our last command, and from each process in<br> # its pipeline. Note: this MUST be the first thing done in this function.<br> __bp_last_ret_value="$?" BP_PIPESTATUS=("${PIPESTATUS[@]}")<br>
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<br> # Don't invoke precmds if we are inside an execution of an "original<br> # prompt command" by another precmd execution loop. This avoids infinite<br> # recursion.<br> if (( __bp_inside_precmd > 0 )); then<br> return<br> fi<br> local __bp_inside_precmd=1<br>
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<br> # Invoke every function defined in our function array.<br> local precmd_function<br> for precmd_function in "${precmd_functions[@]}"; do<br>
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<br> # Only execute this function if it actually exists.<br> # Test existence of functions with: declare -[Ff]<br> if type -t "$precmd_function" 1>/dev/null; then<br> __bp_set_ret_value "$__bp_last_ret_value" "$__bp_last_argument_prev_command"<br> # Quote our function invocation to prevent issues with IFS<br> "$precmd_function"<br> fi<br> done<br>}<br>
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<br># Sets a return value in $?. We may want to get access to the $? variable in our<br># precmd functions. This is available for instance in zsh. We can simulate it in bash<br># by setting the value here.<br>__bp_set_ret_value() {<br> return ${1:-}<br>}<br>
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<br>__bp_in_prompt_command() {<br>
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<br> local prompt_command_array<br> IFS=';' read -ra prompt_command_array <<< "$PROMPT_COMMAND"<br>
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<br> local trimmed_arg<br> trimmed_arg=$(__bp_trim_whitespace "${1:-}")<br>
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<br> local command<br> for command in "${prompt_command_array[@]:-}"; do<br> local trimmed_command<br> trimmed_command=$(__bp_trim_whitespace "$command")<br> # Only execute each function if it actually exists.<br> if [[ "$trimmed_command" == "$trimmed_arg" ]]; then<br> return 0<br> fi<br> done<br>
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<br> return 1<br>}<br>
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<br># This function is installed as the DEBUG trap. It is invoked before each<br># interactive prompt display. Its purpose is to inspect the current<br># environment to attempt to detect if the current command is being invoked<br># interactively, and invoke 'preexec' if so.<br>__bp_preexec_invoke_exec() {<br> # Save the contents of $_ so that it can be restored later on.<br> # <a href="https://stackoverflow.com/questions/40944532/bash-preserve-in-a-debug-trap#40944702" rel="noreferrer noopener">https://stackoverflow.com/questions/40944532/bash-preserve-in-a-debug-trap#40944702</a>
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<br> __bp_last_argument_prev_command="${1:-}"<br> # Don't invoke preexecs if we are inside of another preexec.<br> if (( __bp_inside_preexec > 0 )); then<br> return<br> fi<br> local __bp_inside_preexec=1<br>
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<br> # Checks if the file descriptor is not standard out (i.e. '1')<br> # __bp_delay_install checks if we're in test. Needed for bats to run.<br> # Prevents preexec from being invoked for functions in PS1<br> if [[ ! -t 1 && -z "${__bp_delay_install:-}" ]]; then<br> return<br> fi<br>
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<br> if [[ -n "${COMP_LINE:-}" ]]; then<br> # We're in the middle of a completer. This obviously can't be<br> # an interactively issued command.<br> return<br> fi<br> if [[ -z "${__bp_preexec_interactive_mode:-}" ]]; then<br> # We're doing something related to displaying the prompt. Let the<br> # prompt set the title instead of me.<br> return<br> else<br> # If we're in a subshell, then the prompt won't be re-displayed to put<br> # us back into interactive mode, so let's not set the variable back.<br> # In other words, if you have a subshell like<br> # (sleep 1; sleep 2)<br> # You want to see the 'sleep 2' as a set_command_title as well.<br> if [[ 0 -eq "${BASH_SUBSHELL:-}" ]]; then<br> __bp_preexec_interactive_mode=""<br> fi<br> fi<br>
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<br> if __bp_in_prompt_command "${BASH_COMMAND:-}"; then<br> # If we're executing something inside our prompt_command then we don't<br> # want to call preexec. Bash prior to 3.1 can't detect this at all :/<br> __bp_preexec_interactive_mode=""<br> return<br> fi<br>
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<br> local this_command<br> this_command=$(<br> export LC_ALL=C<br> HISTTIMEFORMAT= builtin history 1 | sed '1 s/^ *[0-9][0-9]*[* ] //'<br> )<br>
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<br> # Sanity check to make sure we have something to invoke our function with.<br> if [[ -z "$this_command" ]]; then<br> return<br> fi<br>
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<br> # If none of the previous checks have returned out of this function, then<br> # the command is in fact interactive and we should invoke the user's<br> # preexec functions.<br>
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<br> # Invoke every function defined in our function array.<br> local preexec_function<br> local preexec_function_ret_value<br> local preexec_ret_value=0<br> for preexec_function in "${preexec_functions[@]:-}"; do<br>
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<br> # Only execute each function if it actually exists.<br> # Test existence of function with: declare -[fF]<br> if type -t "$preexec_function" 1>/dev/null; then<br> __bp_set_ret_value ${__bp_last_ret_value:-}<br> # Quote our function invocation to prevent issues with IFS<br> "$preexec_function" "$this_command"<br> preexec_function_ret_value="$?"<br> if [[ "$preexec_function_ret_value" != 0 ]]; then<br> preexec_ret_value="$preexec_function_ret_value"<br> fi<br> fi<br> done<br>
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<br> # Restore the last argument of the last executed command, and set the return<br> # value of the DEBUG trap to be the return code of the last preexec function<br> # to return an error.<br> # If `extdebug` is enabled a non-zero return value from any preexec function<br> # will cause the user's command not to execute.<br> # Run `shopt -s extdebug` to enable<br> __bp_set_ret_value "$preexec_ret_value" "$__bp_last_argument_prev_command"<br>}<br>
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<br>__bp_install() {<br> # Exit if we already have this installed.<br> if [[ "${PROMPT_COMMAND:-}" == *"__bp_precmd_invoke_cmd"* ]]; then<br> return 1;<br> fi<br>
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<br> trap '__bp_preexec_invoke_exec "$_"' DEBUG<br>
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<br> # Preserve any prior DEBUG trap as a preexec function<br> local prior_trap=$(sed "s/[^']*'\(.*\)'[^']*/\1/" <<<"${__bp_trap_string:-}")<br> unset __bp_trap_string<br> if [[ -n "$prior_trap" ]]; then<br> eval '__bp_original_debug_trap() {<br> '"$prior_trap"'<br> }'<br> preexec_functions+=(__bp_original_debug_trap)<br> fi<br>
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<br> # Adjust our HISTCONTROL Variable if needed.<br> __bp_adjust_histcontrol<br>
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<br>
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<br> # Issue #25. Setting debug trap for subshells causes sessions to exit for<br> # backgrounded subshell commands (e.g. (pwd)& ). Believe this is a bug in Bash.<br> #<br> # Disabling this by default. It can be enabled by setting this variable.<br> if [[ -n "${__bp_enable_subshells:-}" ]]; then<br>
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<br> # Set so debug trap will work be invoked in subshells.<br> set -o functrace > /dev/null 2>&1<br> shopt -s extdebug > /dev/null 2>&1<br> fi;<br>
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<br> # Install our hooks in PROMPT_COMMAND to allow our trap to know when we've<br> # actually entered something.<br> PROMPT_COMMAND="__bp_precmd_invoke_cmd; __bp_interactive_mode"<br>
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<br> # Add two functions to our arrays for convenience<br> # of definition.<br> precmd_functions+=(precmd)<br> preexec_functions+=(preexec)<br>
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<br> # Since this function is invoked via PROMPT_COMMAND, re-execute PC now that it's properly set<br> eval "$PROMPT_COMMAND"<br>}<br>
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<br># Sets our trap and __bp_install as part of our PROMPT_COMMAND to install<br># after our session has started. This allows bash-preexec to be included<br># at any point in our bash profile. Ideally we could set our trap inside<br># __bp_install, but if a trap already exists it'll only set locally to<br># the function.<br>__bp_install_after_session_init() {<br>
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<br> # Make sure this is bash that's running this and return otherwise.<br> if [[ -z "${BASH_VERSION:-}" ]]; then<br> return 1;<br> fi<br>
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<br> # bash-preexec needs to modify these variables in order to work correctly<br> # if it can't, just stop the installation<br> __bp_require_not_readonly PROMPT_COMMAND HISTCONTROL HISTTIMEFORMAT || return<br>
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<br> # If there's an existing PROMPT_COMMAND capture it and convert it into a function<br> # So it is preserved and invoked during precmd.<br> if [[ -n "$PROMPT_COMMAND" ]]; then<br> eval '__bp_original_prompt_command() {<br> '"$PROMPT_COMMAND"'<br> }'<br> precmd_functions+=(__bp_original_prompt_command)<br> fi<br>
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<br> # Installation is finalized in PROMPT_COMMAND, which allows us to override the DEBUG<br> # trap. __bp_install sets PROMPT_COMMAND to its final value, so these are only<br> # invoked once.<br> # It's necessary to clear any existing DEBUG trap in order to set it from the install function.<br> # Using \n as it's the most universal delimiter of bash commands<br> PROMPT_COMMAND=$'\n__bp_trap_string="$(trap -p DEBUG)"\ntrap DEBUG\n__bp_install\n'<br>}<br>
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<br># Run our install so long as we're not delaying it.<br>if [[ -z "$__bp_delay_install" ]]; then<br> __bp_install_after_session_init<br>fi;<br>
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