Bash/Prompt customization

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There are a variety of possibilities for Bash's prompt (PS1), and customizing it can help you be more productive at the command line. You can add additional information to your prompt, or you can simply add color to it to make the prompt stand out.

Basic prompts

The following settings are useful for distinguishing the root prompt from non-root users.

  • Edit Bash's personal configuration file:
$ nano ~/.bashrc
  • Comment out the default prompt:
#PS1='[\u@\h \W]\$ '
  • Add the following green prompt for regular users:
export PS1='\[\e[1;32m\][\u@\h \W]\$\[\e[0m\] '
  • Edit root's Bash file:
# nano /root/.bashrc
  • Assign a red prompt for root:
export PS1='\[\e[1;31m\][\u@\h \W]\$\[\e[0m\] '

Advanced prompts

List of colors for prompt and Bash

Add this to your Bash file(s) to define colors for prompt and commands:

txtblk='\e[0;30m' # Black - Regular
txtred='\e[0;31m' # Red
txtgrn='\e[0;32m' # Green
txtylw='\e[0;33m' # Yellow
txtblu='\e[0;34m' # Blue
txtpur='\e[0;35m' # Purple
txtcyn='\e[0;36m' # Cyan
txtwht='\e[0;37m' # White
bldblk='\e[1;30m' # Black - Bold
bldred='\e[1;31m' # Red
bldgrn='\e[1;32m' # Green
bldylw='\e[1;33m' # Yellow
bldblu='\e[1;34m' # Blue
bldpur='\e[1;35m' # Purple
bldcyn='\e[1;36m' # Cyan
bldwht='\e[1;37m' # White
unkblk='\e[4;30m' # Black - Underline
undred='\e[4;31m' # Red
undgrn='\e[4;32m' # Green
undylw='\e[4;33m' # Yellow
undblu='\e[4;34m' # Blue
undpur='\e[4;35m' # Purple
undcyn='\e[4;36m' # Cyan
undwht='\e[4;37m' # White
bakblk='\e[40m'   # Black - Background
bakred='\e[41m'   # Red
badgrn='\e[42m'   # Green
bakylw='\e[43m'   # Yellow
bakblu='\e[44m'   # Blue
bakpur='\e[45m'   # Purple
bakcyn='\e[46m'   # Cyan
bakwht='\e[47m'   # White
txtrst='\e[0m'    # Text Reset

To use in commands from your shell environment:

$ echo -e "${txtblu}test"
test
$ echo -e "${bldblu}test"
test
$ echo -e "${undblu}test"
test
$ echo -e "${bakblu}test"
test

To use in a prompt (note double quotes and \[ \] used by the shell to count proper length):

PS1="\[$txtblu\]foo\[$txtred\] bar\[$txtrst\] baz : "

Prompt escapes

The various Bash prompt escapes listed in the manpage:

Bash allows these prompt strings to be customized by inserting a
number of backslash-escaped special characters that are
decoded as follows:

  \a         an ASCII bell character (07)
  \d         the date in "Weekday Month Date" format (e.g., "Tue May 26")
  \D{format} the format is passed to strftime(3) and the result
             is inserted into the prompt string an empty format
             results in a locale-specific time representation.
             The braces are required
  \e         an ASCII escape character (033)
  \h         the hostname up to the first `.'
  \H         the hostname
  \j         the number of jobs currently managed by the shell
  \l         the basename of the shell's terminal device name
  \n         newline
  \r         carriage return
  \s         the name of the shell, the basename of $0 (the portion following
             the final slash)
  \t         the current time in 24-hour HH:MM:SS format
  \T         the current time in 12-hour HH:MM:SS format
  \@         the current time in 12-hour am/pm format
  \A         the current time in 24-hour HH:MM format
  \u         the username of the current user
  \v         the version of bash (e.g., 2.00)
  \V         the release of bash, version + patch level (e.g., 2.00.0)
  \w         the current working directory, with $HOME abbreviated with a tilde
  \W         the basename of the current working directory, with $HOME
             abbreviated with a tilde
  \!         the history number of this command
  \#         the command number of this command
  \$         if the effective UID is 0, a #, otherwise a $
  \nnn       the character corresponding to the octal number nnn
  \\         a backslash
  \[         begin a sequence of non-printing characters, which could be used
             to embed a terminal control sequence into the prompt
  \]         end a sequence of non-printing characters
         
  The command number and the history number are usually different:
  the history number of a command is its position in the history
  list, which may include commands restored from the history file
  (see HISTORY below), while the command number is the position in
  the sequence of commands executed during the current shell session.
  After the string is decoded, it is expanded via parameter
  expansion, command substitution, arithmetic expansion, and quote
  removal, subject to the value of the promptvars shell option (see
  the description of the shopt command under SHELL BUILTIN COMMANDS
  below).

Positioning the cursor

The following sequence sets the cursor position:

\[\033[<row>;<column>f\]

The current cursor position can be saved using:

\[\033[s\]

To restore a position, use the following sequence:

\[\033[u\]

The following example uses these sequences to display the time in the upper right corner:

PS1=">\[\033[s\]\[\033[1;\$((COLUMNS-4))f\]\$(date +%H:%M)\[\033[u\]"

The environment variable COLUMNS contains the number of columns of the terminal. The above example substracts 4 from its value in order to justify the five character wide output of date at the right border.

Return value visualisation

Add this line if you want to see the return value of the last executed command. This should work with any kind of prompt as long as it does not need PROMPT_COMMAND:

PROMPT_COMMAND='RET=$?; if [[ $RET=0 ]]; then echo -ne "\033[0;32m$RET\033[0m ;)"; else echo -ne "\033[0;31m$RET\033[0m ;("; fi; echo -n " "'

It will look like this:

0 ;) harvie@harvie-ntb ~/ $ true
0 ;) harvie@harvie-ntb ~/ $ false
1 ;( harvie@harvie-ntb ~/ $ 

Zero is green and non-zero is red. There is also the smiley indication (replace it with anything you want); so your prompt will smile if the last operation was succesful.

Advanced return value visualisation

If you want colors, you need to set $RED and $GREEN values:

RED='\e[0;31m'
GREEN='\e[0;32m'

You have to specify these values in Bash's configuration files:

#return value visualisation
PROMPT_COMMAND='RET=$?;'
RET_VALUE='$(echo $RET)' #Ret value not colorized - you can modify it.
RET_SMILEY='$(if [[ $RET=0 ]]; then echo -ne "\[$GREEN\];)"; else echo -ne "\[$RED\];("; fi;)'

Then you can use $RET_VALUE and $RET_SMILEY variables in the prompt. Note that you need use double quotes:

#prompt
PS1="$RET_VALUE $RET_SMILEY : "

This will give you basic prompt:

0 ;) : true
0 ;) : false
1 ;( : 

But you will probably want to use $RET_VALUE or $RET_SMILEY in your own prompt, like this:

PS1="\[$WHITE\]$RET_VALUE $RET_SMILEY \[$BLUE\]\u\[$RED\]@\[$EBLUE\]\h\[$WHITE\] \W \[$ERED\]\\$\[$EWHITE\] "

Wolfman's

After reading through most of the Bash Prompt Howto, the author developed a color bash prompt that displays the last 25 characters of the current working directory. This prompt should work well on terminals with a black background. The following code goes in file Template:Filename.

  • Add the bash_prompt_command function. If you have a couple directories with long names or start entering a lot of subdirectories, this function will keep the command prompt from wrapping around the screen by displaying at most the last pwdmaxlen characters from the PWD. This code was taken from the Bash Prompt Howto's section on Controlling the Size and Appearance of $PWD and modified to replace the user's home directory with a tilde.
##################################################
# Fancy PWD display function
##################################################
# The home directory (HOME) is replaced with a ~
# The last pwdmaxlen characters of the PWD are displayed
# Leading partial directory names are striped off
# /home/me/stuff          -> ~/stuff               if USER=me
# /usr/share/big_dir_name -> ../share/big_dir_name if pwdmaxlen=20
##################################################
bash_prompt_command() {
    # How many characters of the $PWD should be kept
    local pwdmaxlen=25
    # Indicate that there has been dir truncation
    local trunc_symbol=".."
    local dir=${PWD##*/}
    pwdmaxlen=$(( ( pwdmaxlen < ${#dir} ) ? ${#dir} : pwdmaxlen ))
    NEW_PWD=${PWD/#$HOME/\~}
    local pwdoffset=$(( ${#NEW_PWD} - pwdmaxlen ))
    if [ ${pwdoffset} -gt "0" ]
    then
        NEW_PWD=${NEW_PWD:$pwdoffset:$pwdmaxlen}
        NEW_PWD=${trunc_symbol}/${NEW_PWD#*/}
    fi
}
  • The next fragment generates the command prompt and various colors are defined. The user's color for the username, hostname, and prompt ($ or #) is set to cyan, and if the user is root (root's UID is always 0), set the color to red. The command prompt is set to a colored version of Arch's default with the NEW_PWD from the last function.
Also, make sure that your color variables are enclosed in double and not single quote marks. Using single quote marks seems to give Bash problems with line wrapping correctly.
bash_prompt() {
    case $TERM in
     xterm*|rxvt*)
         local TITLEBAR='\[\033]0;\u:${NEW_PWD}\007\]'
          ;;
     *)
         local TITLEBAR=""
          ;;
    esac
    local NONE="\[\033[0m\]"    # unsets color to term's fg color
    
    # regular colors
    local K="\[\033[0;30m\]"    # black
    local R="\[\033[0;31m\]"    # red
    local G="\[\033[0;32m\]"    # green
    local Y="\[\033[0;33m\]"    # yellow
    local B="\[\033[0;34m\]"    # blue
    local M="\[\033[0;35m\]"    # magenta
    local C="\[\033[0;36m\]"    # cyan
    local W="\[\033[0;37m\]"    # white
    
    # emphasized (bolded) colors
    local EMK="\[\033[1;30m\]"
    local EMR="\[\033[1;31m\]"
    local EMG="\[\033[1;32m\]"
    local EMY="\[\033[1;33m\]"
    local EMB="\[\033[1;34m\]"
    local EMM="\[\033[1;35m\]"
    local EMC="\[\033[1;36m\]"
    local EMW="\[\033[1;37m\]"
    
    # background colors
    local BGK="\[\033[40m\]"
    local BGR="\[\033[41m\]"
    local BGG="\[\033[42m\]"
    local BGY="\[\033[43m\]"
    local BGB="\[\033[44m\]"
    local BGM="\[\033[45m\]"
    local BGC="\[\033[46m\]"
    local BGW="\[\033[47m\]"
    
    local UC=$W                 # user's color
    [ $UID -eq "0" ] && UC=$R   # root's color
    
    PS1="$TITLEBAR ${EMK}[${UC}\u${EMK}@${UC}\h ${EMB}\${NEW_PWD}${EMK}]${UC}\\$ ${NONE}"
    # without colors: PS1="[\u@\h \${NEW_PWD}]\\$ "
    # extra backslash in front of \$ to make bash colorize the prompt
}
  • Finally, append this code. This ensures that the NEW_PWD variable will be updated when you cd somewhere else, and it sets the PS1 variable, which contains the command prompt.
PROMPT_COMMAND=bash_prompt_command
bash_prompt
unset bash_prompt

Set xterm window title

You can use the Template:Codeline variable at the beginning of the prompt to set xterm title (if available) to directory@user@hostname. Or you can modify it using regular prompt escape sequences:

#set xterm title
case "$TERM" in
  xterm | xterm-color)
    XTERM_TITLE='\[\033]0;\W@\u@\H\007\]'
  ;;
esac;

External links