Commit 3b299ccd authored by Per Bothner's avatar Per Bothner

Add helper. Fix some links.

parent 3a62d10e
# -- Bash support for ZSH-like 'preexec' and 'precmd' functions.
# 'preexec' functions are executed before each interactive command is
# executed, with the interactive command as its argument. The 'precmd'
# function is executed before each prompt is displayed.
# Author: Ryan Caloras (
# Forked from Original Author: Glyph Lefkowitz
# V0.3.7
# General Usage:
# 1. Source this file at the end of your bash profile so as not to interfere
# with anything else that's using PROMPT_COMMAND.
# 2. Add any precmd or preexec functions by appending them to their arrays:
# e.g.
# precmd_functions+=(my_precmd_function)
# precmd_functions+=(some_other_precmd_function)
# preexec_functions+=(my_preexec_function)
# 3. Consider changing anything using the DEBUG trap or PROMPT_COMMAND
# to use preexec and precmd instead. Preexisting usages will be
# preserved, but doing so manually may be less surprising.
# Note: This module requires two Bash features which you must not otherwise be
# using: the "DEBUG" trap, and the "PROMPT_COMMAND" variable. If you override
# either of these after bash-preexec has been installed it will most likely break.
# Avoid duplicate inclusion
if [[ "${__bp_imported:-}" == "defined" ]]; then
return 0
# Should be available to each precmd and preexec
# functions, should they want it. $? and $_ are available as $? and $_, but
# $PIPESTATUS is available only in a copy, $BP_PIPESTATUS.
# TODO: Figure out how to restore PIPESTATUS before each precmd or preexec
# function.
# Fails if any of the given variables are readonly
# Reference
__bp_require_not_readonly() {
for var; do
if ! ( unset "$var" 2> /dev/null ); then
echo "bash-preexec requires write access to ${var}" >&2
return 1
# Remove ignorespace and or replace ignoreboth from HISTCONTROL
# so we can accurately invoke preexec with a command from our
# history even if it starts with a space.
__bp_adjust_histcontrol() {
local histcontrol
# Replace ignoreboth with ignoredups
if [[ "$histcontrol" == *"ignoreboth"* ]]; then
export HISTCONTROL="$histcontrol"
# This variable describes whether we are currently in "interactive mode";
# i.e. whether this shell has just executed a prompt and is waiting for user
# input. It documents whether the current command invoked by the trace hook is
# run interactively by the user; it's set immediately after the prompt hook,
# and unset as soon as the trace hook is run.
__bp_trim_whitespace() {
local var=$@
var="${var#"${var%%[![:space:]]*}"}" # remove leading whitespace characters
var="${var%"${var##*[![:space:]]}"}" # remove trailing whitespace characters
echo -n "$var"
# This function is installed as part of the PROMPT_COMMAND;
# It sets a variable to indicate that the prompt was just displayed,
# to allow the DEBUG trap to know that the next command is likely interactive.
__bp_interactive_mode() {
# This function is installed as part of the PROMPT_COMMAND.
# It will invoke any functions defined in the precmd_functions array.
__bp_precmd_invoke_cmd() {
# Save the returned value from our last command, and from each process in
# its pipeline. Note: this MUST be the first thing done in this function.
__bp_last_ret_value="$?" BP_PIPESTATUS=("${PIPESTATUS[@]}")
# Don't invoke precmds if we are inside an execution of an "original
# prompt command" by another precmd execution loop. This avoids infinite
# recursion.
if (( __bp_inside_precmd > 0 )); then
local __bp_inside_precmd=1
# Invoke every function defined in our function array.
local precmd_function
for precmd_function in "${precmd_functions[@]}"; do
# Only execute this function if it actually exists.
# Test existence of functions with: declare -[Ff]
if type -t "$precmd_function" 1>/dev/null; then
__bp_set_ret_value "$__bp_last_ret_value" "$__bp_last_argument_prev_command"
# Quote our function invocation to prevent issues with IFS
# Sets a return value in $?. We may want to get access to the $? variable in our
# precmd functions. This is available for instance in zsh. We can simulate it in bash
# by setting the value here.
__bp_set_ret_value() {
return ${1:-}
__bp_in_prompt_command() {
local prompt_command_array
IFS=';' read -ra prompt_command_array <<< "$PROMPT_COMMAND"
local trimmed_arg
trimmed_arg=$(__bp_trim_whitespace "${1:-}")
local command
for command in "${prompt_command_array[@]:-}"; do
local trimmed_command
trimmed_command=$(__bp_trim_whitespace "$command")
# Only execute each function if it actually exists.
if [[ "$trimmed_command" == "$trimmed_arg" ]]; then
return 0
return 1
# This function is installed as the DEBUG trap. It is invoked before each
# interactive prompt display. Its purpose is to inspect the current
# environment to attempt to detect if the current command is being invoked
# interactively, and invoke 'preexec' if so.
__bp_preexec_invoke_exec() {
# Save the contents of $_ so that it can be restored later on.
# Don't invoke preexecs if we are inside of another preexec.
if (( __bp_inside_preexec > 0 )); then
local __bp_inside_preexec=1
# Checks if the file descriptor is not standard out (i.e. '1')
# __bp_delay_install checks if we're in test. Needed for bats to run.
# Prevents preexec from being invoked for functions in PS1
if [[ ! -t 1 && -z "${__bp_delay_install:-}" ]]; then
if [[ -n "${COMP_LINE:-}" ]]; then
# We're in the middle of a completer. This obviously can't be
# an interactively issued command.
if [[ -z "${__bp_preexec_interactive_mode:-}" ]]; then
# We're doing something related to displaying the prompt. Let the
# prompt set the title instead of me.
# If we're in a subshell, then the prompt won't be re-displayed to put
# us back into interactive mode, so let's not set the variable back.
# In other words, if you have a subshell like
# (sleep 1; sleep 2)
# You want to see the 'sleep 2' as a set_command_title as well.
if [[ 0 -eq "${BASH_SUBSHELL:-}" ]]; then
if __bp_in_prompt_command "${BASH_COMMAND:-}"; then
# If we're executing something inside our prompt_command then we don't
# want to call preexec. Bash prior to 3.1 can't detect this at all :/
local this_command
export LC_ALL=C
HISTTIMEFORMAT= builtin history 1 | sed '1 s/^ *[0-9][0-9]*[* ] //'
# Sanity check to make sure we have something to invoke our function with.
if [[ -z "$this_command" ]]; then
# If none of the previous checks have returned out of this function, then
# the command is in fact interactive and we should invoke the user's
# preexec functions.
# Invoke every function defined in our function array.
local preexec_function
local preexec_function_ret_value
local preexec_ret_value=0
for preexec_function in "${preexec_functions[@]:-}"; do
# Only execute each function if it actually exists.
# Test existence of function with: declare -[fF]
if type -t "$preexec_function" 1>/dev/null; then
__bp_set_ret_value ${__bp_last_ret_value:-}
# Quote our function invocation to prevent issues with IFS
"$preexec_function" "$this_command"
if [[ "$preexec_function_ret_value" != 0 ]]; then
# Restore the last argument of the last executed command, and set the return
# value of the DEBUG trap to be the return code of the last preexec function
# to return an error.
# If `extdebug` is enabled a non-zero return value from any preexec function
# will cause the user's command not to execute.
# Run `shopt -s extdebug` to enable
__bp_set_ret_value "$preexec_ret_value" "$__bp_last_argument_prev_command"
__bp_install() {
# Exit if we already have this installed.
if [[ "${PROMPT_COMMAND:-}" == *"__bp_precmd_invoke_cmd"* ]]; then
return 1;
trap '__bp_preexec_invoke_exec "$_"' DEBUG
# Preserve any prior DEBUG trap as a preexec function
local prior_trap=$(sed "s/[^']*'\(.*\)'[^']*/\1/" <<<"${__bp_trap_string:-}")
unset __bp_trap_string
if [[ -n "$prior_trap" ]]; then
eval '__bp_original_debug_trap() {
# Adjust our HISTCONTROL Variable if needed.
# Issue #25. Setting debug trap for subshells causes sessions to exit for
# backgrounded subshell commands (e.g. (pwd)& ). Believe this is a bug in Bash.
# Disabling this by default. It can be enabled by setting this variable.
if [[ -n "${__bp_enable_subshells:-}" ]]; then
# Set so debug trap will work be invoked in subshells.
set -o functrace > /dev/null 2>&1
shopt -s extdebug > /dev/null 2>&1
# Install our hooks in PROMPT_COMMAND to allow our trap to know when we've
# actually entered something.
PROMPT_COMMAND="__bp_precmd_invoke_cmd; __bp_interactive_mode"
# Add two functions to our arrays for convenience
# of definition.
# Since this function is invoked via PROMPT_COMMAND, re-execute PC now that it's properly set
# Sets our trap and __bp_install as part of our PROMPT_COMMAND to install
# after our session has started. This allows bash-preexec to be included
# at any point in our bash profile. Ideally we could set our trap inside
# __bp_install, but if a trap already exists it'll only set locally to
# the function.
__bp_install_after_session_init() {
# Make sure this is bash that's running this and return otherwise.
if [[ -z "${BASH_VERSION:-}" ]]; then
return 1;
# bash-preexec needs to modify these variables in order to work correctly
# if it can't, just stop the installation
__bp_require_not_readonly PROMPT_COMMAND HISTCONTROL HISTTIMEFORMAT || return
# If there's an existing PROMPT_COMMAND capture it and convert it into a function
# So it is preserved and invoked during precmd.
if [[ -n "$PROMPT_COMMAND" ]]; then
eval '__bp_original_prompt_command() {
# Installation is finalized in PROMPT_COMMAND, which allows us to override the DEBUG
# trap. __bp_install sets PROMPT_COMMAND to its final value, so these are only
# invoked once.
# It's necessary to clear any existing DEBUG trap in order to set it from the install function.
# Using \n as it's the most universal delimiter of bash commands
PROMPT_COMMAND=$'\n__bp_trap_string="$(trap -p DEBUG)"\ntrap DEBUG\n__bp_install\n'
# Run our install so long as we're not delaying it.
if [[ -z "$__bp_delay_install" ]]; then
......@@ -314,7 +314,9 @@ it doesn't have a way to specify a marker.
## Bash shell
If you use [the Bourne-Again SHell (bash)](
use [this initialization script](./shell-integration.bash).
use [this initialization script](./prompts-data/shell-integration.bash).
It depends on the [ script](./prompts-data/
from [this site](
Bash has very limited support for multi-line input editing.
......@@ -326,7 +328,7 @@ If you use [fish shell]( use
## Zsh shell
If you use [Zsh]( use
[this initialization script](./shell-integration.zsh).
[this initialization script](./prompts-data/shell-integration.zsh).
Zsh may leave spurious spaces at the end of a line that is shortened -
see [this bug report](
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