lib/preexec.bash - common/bash_it - Gitiles

 #!/bin/bash
 # http://www.twistedmatrix.com/users/glyph/preexec.bash.txt
 # preexec.bash -- Bash support for ZSH-like 'preexec' and 'precmd' functions.

 # The 'preexec' function is executed before each interactive command is
 # executed, with the interactive command as its argument.  The 'precmd'
 # function is executed before each prompt is displayed.

 # To use, in order:

 #  1. source this file
 #  2. define 'preexec' and/or 'precmd' functions (AFTER sourcing this file),
 #  3. as near as possible to the end of your shell setup, run 'preexec_install'
 #     to kick everything off.

 # Note: this module requires 2 bash features which you must not otherwise be
 # using: the "DEBUG" trap, and the "PROMPT_COMMAND" variable.  preexec_install
 # will override these and if you override one or the other this _will_ break.

 # This is known to support bash3, as well as *mostly* support bash2.05b.  It
 # has been tested with the default shells on MacOS X 10.4 "Tiger", Ubuntu 5.10
 # "Breezy Badger", Ubuntu 6.06 "Dapper Drake", and Ubuntu 6.10 "Edgy Eft".


 # Copy screen-run variables from the remote host, if they're available.

 if [[ "$SCREEN_RUN_HOST" == "" ]]
 then
     SCREEN_RUN_HOST="$LC_SCREEN_RUN_HOST"
     SCREEN_RUN_USER="$LC_SCREEN_RUN_USER"
 fi

 # 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.
 preexec_interactive_mode=""

 # Default do-nothing implementation of preexec.
 function preexec () {
     true
 }

 # Default do-nothing implementation of precmd.
 function precmd () {
     true
 }

 # This function is installed as the PROMPT_COMMAND; it is invoked before each
 # interactive prompt display.  It sets a variable to indicate that the prompt
 # was just displayed, to allow the DEBUG trap, below, to know that the next
 # command is likely interactive.
 function preexec_invoke_cmd () {
     precmd
     preexec_interactive_mode="yes"
 }

 # 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.
 function preexec_invoke_exec () {
     if [[ -n "$COMP_LINE" ]]
     then
         # We're in the middle of a completer.  This obviously can't be
         # an interactively issued command.
         return
     fi
     if [[ -z "$preexec_interactive_mode" ]]
     then
         # We're doing something related to displaying the prompt.  Let the
         # prompt set the title instead of me.
         return
     else
         # 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 "$BASH_SUBSHELL" ]]
         then
             preexec_interactive_mode=""
         fi
     fi
     if [[ "preexec_invoke_cmd" == "$BASH_COMMAND" ]]
     then
         # Sadly, there's no cleaner way to detect two prompts being displayed
         # one after another.  This makes it important that PROMPT_COMMAND
         # remain set _exactly_ as below in preexec_install.  Let's switch back
         # out of interactive mode and not trace any of the commands run in
         # precmd.

         # Given their buggy interaction between BASH_COMMAND and debug traps,
         # versions of bash prior to 3.1 can't detect this at all.
         preexec_interactive_mode=""
         return
     fi

     # In more recent versions of bash, this could be set via the "BASH_COMMAND"
     # variable, but using history here is better in some ways: for example, "ps
     # auxf | less" will show up with both sides of the pipe if we use history,
     # but only as "ps auxf" if not.
     local this_command=`history 1 | sed -e "s/^[ ]*[0-9]*[ ]*//g"`;

     # If none of the previous checks have earlied out of this function, then
     # the command is in fact interactive and we should invoke the user's
     # preexec hook with the running command as an argument.
     preexec "$this_command"
 }

 # Execute this to set up preexec and precmd execution.
 function preexec_install () {

     # *BOTH* of these options need to be set for the DEBUG trap to be invoked
     # in ( ) subshells.  This smells like a bug in bash to me.  The null stderr
     # redirections are to quiet errors on bash2.05 (i.e. OSX's default shell)
     # where the options can't be set, and it's impossible to inherit the trap
     # into subshells.

     set -o functrace > /dev/null 2>&1
     shopt -s extdebug > /dev/null 2>&1

     # Finally, install the actual traps.
     PROMPT_COMMAND="${PROMPT_COMMAND};preexec_invoke_cmd"
     trap 'preexec_invoke_exec' DEBUG
 }

 # Since this is the reason that 99% of everybody is going to bother with a
 # pre-exec hook anyway, we'll include it in this module.

 # Change the title of the xterm.
 function preexec_xterm_title () {
     local title="$1"
     echo -ne "\033]0;$title\007" > /dev/stderr
 }

 function preexec_screen_title () {
     local title="$1"
     echo -ne "\033k$1\033\\" > /dev/stderr
 }

 # Abbreviate the "user@host" string as much as possible to preserve space in
 # screen titles.  Elide the host if the host is the same, elide the user if the
 # user is the same.
 function preexec_screen_user_at_host () {
     local RESULT=""
     if [[ "$SCREEN_RUN_HOST" == "$SCREEN_HOST" ]]
     then
         return
     else
         if [[ "$SCREEN_RUN_USER" == "$USER" ]]
         then
             echo -n "@${SCREEN_HOST}"
         else
             echo -n "${USER}@${SCREEN_HOST}"
         fi
     fi
 }

 function preexec_xterm_title_install () {
     # These functions are defined here because they only make sense with the
     # preexec_install below.
     function precmd () {
         preexec_xterm_title "${TERM} - ${USER}@${SCREEN_HOST} `dirs -0` $PROMPTCHAR"
         if [[ "${TERM}" == screen ]]
         then
             preexec_screen_title "`preexec_screen_user_at_host`${PROMPTCHAR}"
         fi
     }

     function preexec () {
         preexec_xterm_title "${TERM} - $1 {`dirs -0`} (${USER}@${SCREEN_HOST})"
         if [[ "${TERM}" == screen ]]
         then
             local cutit="$1"
             local cmdtitle=`echo "$cutit" | cut -d " " -f 1`
             if [[ "$cmdtitle" == "exec" ]]
             then
                 local cmdtitle=`echo "$cutit" | cut -d " " -f 2`
             fi
             if [[ "$cmdtitle" == "screen" ]]
             then
                 # Since stacked screens are quite common, it would be nice to
                 # just display them as '$$'.
                 local cmdtitle="${PROMPTCHAR}"
             else
                 local cmdtitle=":$cmdtitle"
             fi
             preexec_screen_title "`preexec_screen_user_at_host`${PROMPTCHAR}$cmdtitle"
         fi
     }

     preexec_install
 }
	#!/bin/bash
	# http://www.twistedmatrix.com/users/glyph/preexec.bash.txt
	# preexec.bash -- Bash support for ZSH-like 'preexec' and 'precmd' functions.

	# The 'preexec' function is executed before each interactive command is
	# executed, with the interactive command as its argument. The 'precmd'
	# function is executed before each prompt is displayed.

	# To use, in order:

	# 1. source this file
	# 2. define 'preexec' and/or 'precmd' functions (AFTER sourcing this file),
	# 3. as near as possible to the end of your shell setup, run 'preexec_install'
	# to kick everything off.

	# Note: this module requires 2 bash features which you must not otherwise be
	# using: the "DEBUG" trap, and the "PROMPT_COMMAND" variable. preexec_install
	# will override these and if you override one or the other this _will_ break.

	# This is known to support bash3, as well as mostly support bash2.05b. It
	# has been tested with the default shells on MacOS X 10.4 "Tiger", Ubuntu 5.10
	# "Breezy Badger", Ubuntu 6.06 "Dapper Drake", and Ubuntu 6.10 "Edgy Eft".


	# Copy screen-run variables from the remote host, if they're available.

	if [[ "$SCREEN_RUN_HOST" == "" ]]
	then
	SCREEN_RUN_HOST="$LC_SCREEN_RUN_HOST"
	SCREEN_RUN_USER="$LC_SCREEN_RUN_USER"
	fi

	# 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.
	preexec_interactive_mode=""

	# Default do-nothing implementation of preexec.
	function preexec () {
	true
	}

	# Default do-nothing implementation of precmd.
	function precmd () {
	true
	}

	# This function is installed as the PROMPT_COMMAND; it is invoked before each
	# interactive prompt display. It sets a variable to indicate that the prompt
	# was just displayed, to allow the DEBUG trap, below, to know that the next
	# command is likely interactive.
	function preexec_invoke_cmd () {
	precmd
	preexec_interactive_mode="yes"
	}

	# 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.
	function preexec_invoke_exec () {
	if [[ -n "$COMP_LINE" ]]
	then
	# We're in the middle of a completer. This obviously can't be
	# an interactively issued command.
	return
	fi
	if [[ -z "$preexec_interactive_mode" ]]
	then
	# We're doing something related to displaying the prompt. Let the
	# prompt set the title instead of me.
	return
	else
	# 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 "$BASH_SUBSHELL" ]]
	then
	preexec_interactive_mode=""
	fi
	fi
	if [[ "preexec_invoke_cmd" == "$BASH_COMMAND" ]]
	then
	# Sadly, there's no cleaner way to detect two prompts being displayed
	# one after another. This makes it important that PROMPT_COMMAND
	# remain set _exactly_ as below in preexec_install. Let's switch back
	# out of interactive mode and not trace any of the commands run in
	# precmd.

	# Given their buggy interaction between BASH_COMMAND and debug traps,
	# versions of bash prior to 3.1 can't detect this at all.
	preexec_interactive_mode=""
	return
	fi

	# In more recent versions of bash, this could be set via the "BASH_COMMAND"
	# variable, but using history here is better in some ways: for example, "ps
	# auxf \| less" will show up with both sides of the pipe if we use history,
	# but only as "ps auxf" if not.
	local this_command=`history 1 \| sed -e "s/^[ ][0-9][ ]*//g"`;

	# If none of the previous checks have earlied out of this function, then
	# the command is in fact interactive and we should invoke the user's
	# preexec hook with the running command as an argument.
	preexec "$this_command"
	}

	# Execute this to set up preexec and precmd execution.
	function preexec_install () {

	# BOTH of these options need to be set for the DEBUG trap to be invoked
	# in ( ) subshells. This smells like a bug in bash to me. The null stderr
	# redirections are to quiet errors on bash2.05 (i.e. OSX's default shell)
	# where the options can't be set, and it's impossible to inherit the trap
	# into subshells.

	set -o functrace > /dev/null 2>&1
	shopt -s extdebug > /dev/null 2>&1

	# Finally, install the actual traps.
	PROMPT_COMMAND="${PROMPT_COMMAND};preexec_invoke_cmd"
	trap 'preexec_invoke_exec' DEBUG
	}

	# Since this is the reason that 99% of everybody is going to bother with a
	# pre-exec hook anyway, we'll include it in this module.

	# Change the title of the xterm.
	function preexec_xterm_title () {
	local title="$1"
	echo -ne "\033]0;$title\007" > /dev/stderr
	}

	function preexec_screen_title () {
	local title="$1"
	echo -ne "\033k$1\033\\" > /dev/stderr
	}

	# Abbreviate the "user@host" string as much as possible to preserve space in
	# screen titles. Elide the host if the host is the same, elide the user if the
	# user is the same.
	function preexec_screen_user_at_host () {
	local RESULT=""
	if [[ "$SCREEN_RUN_HOST" == "$SCREEN_HOST" ]]
	then
	return
	else
	if [[ "$SCREEN_RUN_USER" == "$USER" ]]
	then
	echo -n "@${SCREEN_HOST}"
	else
	echo -n "${USER}@${SCREEN_HOST}"
	fi
	fi
	}

	function preexec_xterm_title_install () {
	# These functions are defined here because they only make sense with the
	# preexec_install below.
	function precmd () {
	preexec_xterm_title "${TERM} - ${USER}@${SCREEN_HOST} `dirs -0` $PROMPTCHAR"
	if [[ "${TERM}" == screen ]]
	then
	preexec_screen_title "`preexec_screen_user_at_host`${PROMPTCHAR}"
	fi
	}

	function preexec () {
	preexec_xterm_title "${TERM} - $1 {`dirs -0`} (${USER}@${SCREEN_HOST})"
	if [[ "${TERM}" == screen ]]
	then
	local cutit="$1"
	local cmdtitle=`echo "$cutit" \| cut -d " " -f 1`
	if [[ "$cmdtitle" == "exec" ]]
	then
	local cmdtitle=`echo "$cutit" \| cut -d " " -f 2`
	fi
	if [[ "$cmdtitle" == "screen" ]]
	then
	# Since stacked screens are quite common, it would be nice to
	# just display them as '$$'.
	local cmdtitle="${PROMPTCHAR}"
	else
	local cmdtitle=":$cmdtitle"
	fi
	preexec_screen_title "`preexec_screen_user_at_host`${PROMPTCHAR}$cmdtitle"
	fi
	}

	preexec_install
	}