Linux How-To wiki

Dynamic Method

Not everyone appreciates a lot of information in their BASH prompt. Some admins find it confusing and prefer the standard prompt or just some minor changes. So I came up with a way to make the prompt adjustable so it can be installed system-wide and configured individually. It dynamically reads the settings every time, so changes made to its configuration do not require it to be reloaded.

The files involved are these:

File name	Description	Global location	Personal location
prompt	A tool to change the PS1 prompt. It is sourced rather than run because if run then the settings are lost when the script exits.	/usr/local/bin/	$HOME/bin/
z-bash-prompt.sh	A script that sets the PS1 prompt to be a dynamic script rather than static string. I named it with a `z-` prefix so that if it is placed in `/etc/profile.d` it will be called last.	/etc/profile.d/	$HOME/bin/
prompt.bash	The script that actually draws the prompt each time.	/usr/local/sbin/	$HOME/bin/
colours.sh	A file defining ANSI colour codes. Without it you will have a monochrome prompt.	/usr/local/bin/	$HOME/bin/

z-bash-prompt.sh

Show/Hide the code for z-bash-prompt.sh

#!/bin/bash
# BASH enhancements             Angelo Babudro          ispltd.org
# Set a colourful & helpful command prompt
#
# Place this file in /etc/profile.d/ to be automatically sourced at every
# log-in by /etc/profile.
#
# Soft dependency:  colours.sh, ANSI terminal escape sequence definitions for
# the MYSQL_PS1 prompt.  Without it that prompt will be monochrome.

#|Not an interactive shell?  No point in setting the prompt.
[[ $- != *i* ]] && return;

bpf="$HOME/.bash-prompt"
[ -s $bpf ] || bpf="$HOME/bin/prompt.bash"
[ -s $bpf ] || bpf="/usr/local/bin/prompt.bash"
[ -s $bpf ] || bpf="/etc/profile.d/prompt.bash"
if [ -s $bpf ]
then
        function prompt_command {
                export PS1=$($bpf)
        }
        export -f prompt_command
        export PROMPT_COMMAND=prompt_command
fi

for foo in /usr/local/bin usr/local/bin /etc/profile.d etc/profile.d
do
        test -s ${foo}/colours.sh && source ${foo}/colours.sh
done
MachineColour="${White}${bg_Blue}"

MYSQL_PS1="${MachineColour}\h${Reset} ${Cyan}\w \R:\m:\s  ${Yellow}\d${Cyan}  \c${Reset}| "
export MYSQL_PS1

# vim:ts=3:sw=3

I had originally named the above script 04-bash-prompt.sh, but files named vte*sh in /etc/profile.d/ later appeared that also set PS1 and would override my settings. So I renamed the script to start with “z” so it gets executed last when /etc/profile iterates through all the *.sh files in /etc/profile.d/.

prompt.bash

Show/Hide the code for /etc/profile.d/prompt.bash

Save the below code as any of the names referenced in the above script.

#!/bin/bash
# vim: ts=3 sw=3:
# BASH prompt enhancements
# Summer 2017	Angelo Babudro	Creation
# Sundry times	Angelo Babudro	Frequent small enhancements
# 29-Feb-2020	Angelo Babudro	Improvements for TMUX and Ubuntu compatibility
#
# Place this file in /etc/profile.d/ and also create another script
# named z-bash-prompt.sh in that directory that has this:
#	bpf="$HOME/.prompt.bash"
#	[ -e "$bpf" ] || bpf="$HOME/prompt.bash"
#	[ -e "$bpf" ] || bpf="/etc/profile.d/prompt.bash"
#	if [[ -s "$bpf" && -x "$bpf" ]];    #|Exists, >0 bytes, and executable
#	then
#		prompt_command() {
#			export PS1=$($bpf)
#		}   
#		export PROMPT_COMMAND=prompt_command
#	fi

# If running a BASH emulator in Windows the hostname command may not have a '-s' flag.
longname=$(hostname)
shortname=${longname%%.*}

# --[ custom machine definitions ]--------------------
if [[ $longname =~ prod|prd|PRD ]]
then
	purpose="prod"
elif [[ $longname =~ dns ]]
then
	purpose="prod dns"
elif [[ $longname =~ ^uat ]]
then
	purpose="uat"
elif [[ $longname =~ ^dev ]]
then
	purpose="dev"
fi

# Special prompt characters from BASH man page:
#  \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 (uses the value of the PROMPT_DIRTRIM variable)
#  \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

# Users control which enhancements they want using BP* variables below.
# Prompt can, thus, be dynamically altered, e.g.: export BPshowColour=1

# put a copy in home directory to override the global defaults.
# Which features would you like to include in your BASH prompt?
# 0 = do not use this feature
# 1 = include this feature
# Any changes to these variables will immediately take effect so you can experiment easily.

showColour=${BPshowColour:-0}		;# Use colours or just leave everything in the standard terminal attribute?
showAddresses=${BPshowAddresses:-0}	;# Show IP addresses?  If no, user@hostname default format is used.
showTime=${BPshowTime:-0}			;# Show date and time at the right-hand margin?
showKernel=${BPshowKernel:-0}		;# Show the kernel version at the right-hand margin?
showHistNo=${BPshowHistNo:-0}		;# Show the command history number at each prompt?
showOS=${BPshowOS:-0}				;# Show the O/S version, e.g., "Oracle Linux 7.3"?
showUptime=${BPshowUptime:-0}		;# Show the server up-time, to spot unscheduled reboots
showRAM=${BPshowRAM:-0}				;# Show the total & free RAM

# Path display setings:
# 0 = show the shortest path name possible for showPath.
# 1 = show the standard path, using the ~ to represent the HOME directory
#	NB: the tilde (~) display can be incorrect since it depends on the HOME variable.
# 2 = show full/true path on its own line for a consistent look even when paths are long.
showPath=${BPshowPath:-1}

let showSum=0
for var in $showColour $showAddresses $showTime $showKernel $showHistNo $showOS $showUptime $showRAM $showPath
do
	let showSum+=$var
done
#______[ end of enhancement settings ]______________

uptime_string() {
	if [[ $VERSION =~ ^6 ]]
	then
		uptime|sed -r 's/[0-9:]+//; s/,[ ]+[0-9]+ user[s]?.*//;'
	else
		uptime -p|sed -r 's/ year[s]?,/y/; s/ month[s]?,/M/; s/ week[s]?,/w/; s/ day[s]?,/d/; s/ hour[s]?,/h/; s/ minute[s]?/m/;'
	fi
}
CPU_count() {
	kc=$(grep "core id" /proc/cpuinfo|sort -u|wc -l)
	echo "$kc-core"
}
RAM() {
	[[ $showRAM -eq 0 ]] && return
	if [ `uname` = "SunOS" ]
	then
		fmem=`/usr/sbin/prtconf | grep Mem | awk '{print $3}'`;			#|Megabytes
		fGB="${fmem}MB"
	else
		tmem=$(free | grep Mem | awk '{print $2}');							#|Total Kilobytes
		fmem=$(free | grep Mem | awk '{print $4}');							#|Free Kilobytes
		tGB=$(echo "scale=1; ${tmem}/1024/1024" | bc -q 2>/dev/null);	#|Gigabytes
		fGB=$(echo "scale=1; ${fmem}/1024/1024" | bc -q 2>/dev/null);	#|Gigabytes
		tGB="${tGB}GB"
		fGB="${fGB}GB"
	fi
	printf "%s/%s" "$fGB" "$tGB"
}
#______[ end of functions ]______________

# Flush history with each command, so if the session times-out all history will be saved.
history -a
# Can't use 'history -n' in here to load new lines from other sessions.

function TruePath {
	pwd
}
if [ "$showColour" = "1" ]
then
	RESET=$'\[\e[0m\]'
	PATHCOLOUR=$'\[\e[0;37m\]'
	YELLOW=$'\[\e[1;33m\]'
	BLUE=$'\[\e[1;34m\]'
	CYAN=$'\[\e[0;36m\]'
	WARN=$'\[\e[1;37;41m\]'
	UCOLOUR=$'\[\e[1;33;44m\]'
	[[ $((showAddresses+showOS+showPath)) -lt 2 ]] && UCOLOUR=$'\[\e[1;33m\]'
	HOSTCOLOUR=$'\[\e[1;4;36m\]'
else
	BLUE=""
	CYAN=""
	PATHCOLOUR=""
	WARN=""
	HOSTCOLOUR=""
	RESET=""
	[[ $showSum -le 1 ]] && UCOLOUR="[" || UCOLOUR=""
	YELLOW=""
fi
[[ -x /usr/bin/which ]] && which="/usr/bin/which" || which="/bin/which"
[[ -n $($which tput 2>/dev/null) ]] && cols=$(tput cols) || cols=100
dt=""
if [ "$showTime" = "1" ]
then
	dt=$(date +"%a %d-%b %H:%M:%S %Z")
	let tabdate=cols-${#dt}
	dt=$'\[\r\e['"${tabdate}C\]${CYAN}${dt}${RESET}"
fi
[ -n "$($which ifconfig 2>/dev/null)" ] && ipbin="$($which ifconfig)"
[ -n "$($which ip 2>/dev/null)" ] && ipbin="$($which ip) addr list"


if [[ -z $purpose ]]
then
	purpose=$shortname
fi
if [[ $purpose =~ tst|TST|test|dev|DEV ]]
then
	tier="$BLUE DEV"
elif [[ $purpose =~ stg|STG|stage|STAGE|uat|UAT ]]
then
	tier+="$YELLOW UAT"
elif [[ $purpose =~ prd|PRD|prod|PROD ]]
then
	#|Put an extra space before colour change in Prod since it changes the background
	tier+=" $WARN PROD"
else
	tier+="$BLUE (?)"
fi
[[ $purpose =~ dns ]] && tier+=" DNS"
tier+=" ${RESET}"

IPaddr=""
HN=""
if [[ $showAddresses -ne 0 ]]
then
	if [ -n "$ipbin" ]
	then
		first4=""
		last3=""
		for addr in $($ipbin 2>/dev/null | grep -oE "inet [0-9]+.[0-9.]+")
		do
			[[ $addr =~ inet || $addr =~ 127.0.0 ]] && continue
			# If the server has a lot of IP address in sequence then
			# show the range rather than every address.
			oct4=${addr##*.}
			first3=${addr%.*}
			if [[ $last3 == $first3 ]]; then
				[[ -z $first4 ]] && first4=$oct4
			else
				if [[ -n $first4 ]]; then
					IPaddr+=" $first3.$first4-$oct4"
					first4=""
				else
					IPaddr+=" $addr"
				fi
			fi
			last3="$first3"
		done
		[[ -n $first4 ]] && IPaddr+=" to $oct4"
		IPaddr=${IPaddr:1}
	else
		IPaddr=$(ipconfig |grep IPv4|grep -Eo "[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+")
		IPaddr=$(echo $IPaddr);							#|Combine into one line, remove Carriage Returns
	fi
	[[ $showAddresses -lt 2 ]] && tier=""
	IPaddr=${HOSTCOLOUR}$shortname$RESET${tier}${CYAN}"  $IPaddr"
else
	HN="@\h"
fi

OS=""
if [ "$showOS" = "1" ]
then
	if [ -e /etc/os-release ] 
	then
		. /etc/os-release
		case $NAME in
			Oracle*)
				OS="OEL${VERSION}"
				;;
			Red*)
				OS="RHEL${VERSION}"
				;;
			*)
				OS="${NAME% Server} $VERSION"
				;;
		esac
	elif [ -e /etc/redhat-release ]
	then
		OS="RHEL $(sed -r 's/.*release ([0-9.]+) .*/\1/;' /etc/redhat-release)"
	else
		OS="Cygwin"
	fi
	OS="$(CPU_count)  $OS"
fi

if [ "$showUptime" = "1" ]
then
	[ -n "$IPaddr" ] && IPaddr+="  "
	IPaddr+="$(uptime_string)"
fi
[ -n "$IPaddr" ] && IPaddr+="$RESET"

kernel=""
if [ "$showKernel" = "1" ]
then
	if [ -x /bin/uptrack-uname ]
	then
		kernel=$(uptrack-uname -r 2>/dev/null)
		[ -z "$kernel" ] && kernel=$(uname -r)
	else
		kernel=$(uname -r)
	fi
	kernel=${kernel%.x86_64}
	kernel="${OS}  ${kernel}"
elif [[ $showOS -eq 1 ]]
then
	kernel="${OS}"
fi
if [[ -n $kernel ]]; then
	let right[2]=cols-${#kernel}
	kernel+="$RESET"
fi

RAMtext=""
if [[ $showRAM -eq 1 ]]
then
	RAMtext="$(RAM)  "
	let right[2]-=${#RAMtext}
fi
tmuxtitle=$(printf "\033k$shortname\033\\");		#|Command ends in "\"
tmuxtitle+="\\";													#|Need 2nd "\"; does not work if put above
tmuxtitle+=$(printf "\033]2$(whoami)")
[ -n $SH_LEVEL ] && gterm="\[\e]0;\h\a\]";				#|set gterm title:  \e]0; + the title + \a
# KDE Konsole uses same \e]0;(text)\a as gterm.  Just enable Konsole's setting "Set tab to match window title".
if [[ $TERM =~ screen || -n $TMUX ]]
then
	[[ ! $TERM =~ xterm ]] && gterm="\[${tmuxtitle}\]";
fi
[ "$TERM" = "linux" ] && gterm=""

[ -n "${IPaddr}${OS}${dt}" ] && dt="${dt}"$'\n'
declare -a path
path[3]=" "
[[ $((showKernel+showOS)) -gt 0 ]] && pathLine=2 || pathLine=3
path[$pathLine]=" $PATHCOLOUR"
case $showPath in
	0)	path[$pathLine]+=$(basename `pwd`)
		;;
	1)	path[$pathLine]+="\w"
		;;
	2)	path[$pathLine]+=$(TruePath)
		;;
esac
[[ $showSum -le 1 && $showColour -eq 0 ]] && path[$pathLine]+="]" || path[$pathLine]+=" "

[ $showHistNo -eq 1 ] && HistNo='\#' || HistNo=""

	let lines=0
[ $((showAddresses+showUptime+showTime)) -gt 0 ] && ((lines++))
[[ $((showKernel+showOS)) -gt 0 ]] && { ((lines++)); kernel="$kernel"$'\n'; }
[ $lines -gt 0 ] && IPaddr=$'\n'"$IPaddr"
if [[ $lines -gt 1 ]]
then
	if [[ $UID -eq 0 ]]
	then
		UserName="${UCOLOUR} • R00T • "
		fontgeo=$(showconsolefont -i 2>/dev/null)
		if [[ -z $fontgeo ]];		#|In an SSH session showconsolefont will not work, so fall-back to checking the config file
		then
			cfontdef="/etc/vconsole.conf"
			[[ -e $cfontdef ]] || cfontdef="/etc/conf.d/consolefont"
			if [[ -e $cfontdef && $(grep -cE "^[a-z].*(iso|sun)" $cfontdef) -gt 0 ]]
			then
				fontgeo="12x22x256"
			fi
		fi
		if [[ $fontgeo =~ 12x22x256 ]]
		then
			UserName="${UCOLOUR} ∙ R00T ∙ "
		fi
	else
		UserName=" ${UCOLOUR}$USER"                                                                          
	fi
else
	UserName="${UCOLOUR}${USER}"
fi

echo -n "${gterm}${RESET}${IPaddr}${dt}"
echo -n "${path[2]}${RESET}"$'\[\r\e['${right[2]}"C\]${CYAN}${RAMtext}${kernel}"
echo -n "${UserName}${HN}${RESET}${path[3]}${HistNo}\\$ "

colours.sh

Here is an example colours.sh file that you can edit to suit your needs:

Show/Hide the code for colours.sh

#!/bin/bash
# vim: ts=8 sw=8:
# Define ANSI escape sequences for colours and cursor control, for use in scripts.
# Angelo Babudro ispltd.org
#
#Black       0;30     Dark Grey     1;30	Set background colours by using 40 instead of 30:
#Blue        0;34     Light Blue    1;34	 44 for Blue background, 41 for a Red background, etc.
#Green       0;32     Light Green   1;32
#Cyan        0;36     Light Cyan    1;36
#Red         0;31     Light Red     1;31	Combinations can be used, e.g., Light Red text on a Blue background:
#Purple      0;35     Light Purple  1;35	 \[\033[44;1;31m\], although setting the colours separately
#Brown       0;33     Yellow        1;33	 seems to work better (ie. \[\033[44m\]\[\033[1;31m\]).
#Light Grey  0;37     White         1;37
#
# Attribute codes 1:bold 2:faint 3:italic 4:Underscore 5:slow blink 6:rapid blink 7:Invert 8:Conceal 9:cross-out
#
# References:
#	http://www.termsys.demon.co.uk/vtansi.htm (good, although not entirely complete)
#	http://en.wikipedia.org/wiki/ANSI_escape_code (not very complete)
#	http://hackage.haskell.org/packages/archive/ansi-terminal/0.5.0/doc/html/System-Console-ANSI.html (not as clear)

# Bright colours
Red=$'\e[1;31m'
Orange=$'\e[01;31m'
Olive=$'\e[01;32m'
Yellow=$'\e[01;33m'
Blue=$'\e[01;34m'
Pink=$'\033[01;35m'
LtCyan=$'\e[01;36m'
White=$'\033[01;37m'

# Dim colours

Brick=$'\e[00;31m'
Green=$'\e[00;32m'
Brown=$'\e[00;33m'
Navy=$'\e[00;34m'
Purple=$'\e[00;35m'
Cyan=$'\e[00;36m'
Grey=$'\e[00;37m'
Gray=$'\e[00;37m'

# Background colours

bg_Black=$'\e[40m'
bg_Red=$'\e[41m'
bg_Green=$'\e[42m'
bg_Brown=$'\e[43m'
bg_Blue=$'\e[44m'
bg_Purple=$'\e[45m'
bg_Cyan=$'\e[46m'
bg_Grey=$'\e[47m'

# Common FG+BG attributes
# Names mean FG-on-BG

AoK=$'\e[0;37;40m';	# Gray on black ('ay' sounds like A)
BoW=$'\e[1;34;47m';		# Blue on white
CoK=$'\e[0;36;40m';	# Cyan on black
GoK=$'\e[0;32;40m';	# Green on black
GroK=$'\e[0;37;40m';	# Grey on black (deprecated in favour of 3-char AoK)
KoB=$'\e[0;30;44m';			# Black on blue (dark)
KoG=$'\e[0;30;42m';			# Black on green
KoW=$'\e[1;30;47m';		# Black on white
KoY=$'\e[1;30;42m';			# Black on yellow
MoK=$'\e[0;35;40m';	# Magenta on black
OoK=$'\e[1;32;40m';	# Olive on black
PoK=$'\e[0;35;40m';	# Purple on black
RoK=$'\e[1;31;40m';	# Red on black
WoB=$'\e[1;37;44m';			# White on blue
WoK=$'\e[1;37;40m';	# White on black
WoR=$'\e[1;37;41m';			# White on red
YoB=$'\e[1;33;44m';			# Yellow on blue
YoK=$'\e[1;33;40m';	# Yellow on black

# Other attributes

Dim=${Cyan}
Bold=$'\e[1m'
Underline=$'\e[4m'
Reset=$'\e[0m'
Normal=$'\e[0m'
Invert=$'\e[0;7m';
Inverse=${Invert}
#Title=${Invert}
Title=$'\e[1;44m'
Error=$'\e[1;37;41m'

# Actions

EraseEOL=$'\e[0K';		#|Erase from cursor to end of line
EraseBOL=$'\e[1K';		#|Erase from cursor to beginning of line
EraseLine=$'\e[2K';		#|Erase entire line, leave cursor position unchanged
EraseEOS=$'\e[J';		#|Erase from current line to end of screen
EraseBOS=$'\e[1J';		#|Erase from current line to beginning of screen
CLS=$'\e[2J';			#|Clear screen

# Cursor control

SaveCursor=$'\e[s';		#|Save cursor position
RestCursor=$'\e[u';		#|Restore cursor to last saved position
SaveAttrs=$'\e[7';		#|Save cursor position and attributes
RestAttrs=$'\e[8';		#|Restore cursor position and attributes
GoHome=$'\e[H';			#|Move to position {1,1}
SetTab=$'\eH';			#|Set TAB at current position
ClearTab=$'\e[g';		#|Clear TAB at current position
ClearAllTabs=$'\e[3g';

# Ones that have dynamic parameters:
#	<ESC>[{ROW};{COLUMN}f		Force cursor position to be ROW, COLUMN
#	<ESC>[{COUNT}C			Cursor forward COUNT spaces
#	<ESC>[{COUNT}D			Cursor backward COUNT spaces

#	<ESC>[r				Enable scrolling for entire screen
#	<ESC>[{start};{end}r		Enable scrolling from {start} to {end} rows

prompt

The prompt script to alter the prompt on-demand:

Show/hide /usr/local/bin/prompt script

#!/bin/bash
# vim:		ts=4 sw=4:
# Author	Angelo Babudro
# Synopsis	Set BASH prompt enhancements using a command.
#			Source this file -- do not run it.  It will warn if you try to do that.
# Log		June 2017	Creation
#			2019		Added 'save' function

[[ $- =~ i ]] || return &>/dev/null
[[ -t 0 ]] || return &>/dev/null
$(return &>/dev/null)
if [[ "$?" -ne "0" ]]
then
	echo "Please source this script rather than running it."
	echo "Try this:  . prompt help"
	echo "      or:  source prompt help"
	# Be extra-sure that we do not "exit" from a log-in shell:
	return &>/dev/null || exit
fi
help() {
	printf "\e[1;33;44mBASH prompt setting\e[0m\n"
	[[ $0 =~ bash ]] || printf "Please source this script, rather than running it, i.e.:\n\t\e[1;33m. $(basename $0) $*\e[0m\n"
	printf "If no parameters are passed it will just show the current settings.\n\n"
	printf "Pass the first letter of a setting name to toggle it.\n"
	printf "e.g., \e[1;4;33mc\e[0m toggles colour.\n"
	printf "      \e[1;4;33mT\e[0m toggles the display of the current date and time.\n"
	printf "Pass \e[1;4;33msave\e[0m to save/replace the current settings in your ~/.bashrc file.\n"
	#for var in $(env|'grep' BPshow)
	#do
	#	printf "\e[0;36;40m%s\e[0m\n" $var
	#done
	#printf "\e[0;36;40mexport "
	#for var in $(env|'grep' BPshow)
	#do
	#	printf "%s " ${var%%=*}
	#done
	printf "\e[0m\n"
	printf "\n\e[4mShortcuts\e[0m\n"
	printf "❶ To enable all of the prompt features use the key word \e[1;33mall\e[0m.\n"
	printf "❷ To disable everything, giving a stock prompt, pass \e[1;33mnone\e[0m or \e[1;33mstd\e[0m.\n"
	printf "❸ Multiple toggles can be passed with spaces, e.g., c a h\n"
	printf "\nThe status display shows a one-letter idenfier for each variable:\n"
	#printf "C=colour, A=address, D=date, K=kernel, H=history, O=O/S, U=uptime, R=RAM, P=path\n"
	printf "Colour\n"
	printf "| Address(es) (0=none, 1=addresses, 2=addr+use)\n"
	printf "| | Date+Time\n"
	printf "| | | Kernel\n"
	printf "| | | | History count\n"
	printf "| | | | | O/S version\n"
	printf "| | | | | | Up time\n"
	printf "| | | | | | | Free RAM\n"
	printf "| | | | | | | | Path (0=short, 1=default, 2=full)\n"
	return
}
save() {
	expStr="export "
	for var in $(env|'grep' BPshow)
	do
		baseVar=${var%%=*}
		sed -r "/.*${baseVar}=.*/d;" -i ~/.bashrc
	  	echo "$var" >> ~/.bashrc
		expStr+="$baseVar "
	done
	expStr=${expStr% }
	# For the export, ONLY search for a complete match, in case the user has put other vars on the export line.
	# So we might end up with variables exported twice; no big deal.
	grep -q "$expStr" ~/.bashrc || echo "$expStr" >> ~/.bashrc
	printf "\e[1;4mCurrent settings saved in $HOME/.bashrc\e[0m\n"
}

toggle() {
	[[ -z $1 ]] && return
	for BPvar in $(env|grep BPshow)
	do
		var=${BPvar%=*}
		ltr=${var#*how}
		if [[ ${ltr,,} =~ ^${1,,} ]]; then
			printf "\e[0;32m%s\e[0m\n" $ltr
			if [[ ${var,,} =~ path|addr ]];			#|These two can be 0, 1, or 2
			then
				value=$(eval "echo \$$var")
				let value+=1
				[[ $value -gt 2 ]] && value=0
			else
				[[ $(eval "echo \$$var") == "0" ]] && value=1 || value=0
			fi
			eval $var=$value
		fi
	done
}

while [[ -n $1 ]]
do
	case $1 in
		all)
			BPshowColour=1					;# Use colours
			BPshowAddresses=2				;# Show IP addresses: 0=no, 1=yes, 2=w/purpose
			BPshowTime=1					;# Show date and time at the right-hand margin
			BPshowKernel=1					;# Show the kernel version at the right-hand margin
			BPshowHistNo=1					;# Show the command history number at each prompt
			BPshowOS=1						;# Show the O/S version, e.g., "Oracle Linux 7.3"
			BPshowUptime=1					;# Show up-time to spot unscheduled reboots
			BPshowRAM=1						;# Show free/total RAM
			BPshowPath=2					;# 0=shortest, 1=default, 2=full path
			;;
		none|std|standard|norm)
			BPshowColour=0
			BPshowAddresses=0
			BPshowTime=0
			BPshowKernel=0
			BPshowHistNo=0
			BPshowOS=0
			BPshowUptime=0
			BPshowRAM=0
			BPshowPath=1
			;;
		help)
			help
			;;
		save)
			save
			;;
		*)
			toggle $1
			;;
	esac
	shift
done

export BPshowColour BPshowAddresses BPshowTime BPshowKernel BPshowHistNo BPshowOS BPshowUptime BPshowRAM BPshowPath
if [[ -t 0 ]]; then
	for var in BPshowColour BPshowAddresses BPshowDate BPshowTime BPshowKernel BPshowHistNo BPshowOS BPshowUptime BPshowRAM BPshowPath
	do
		[[ -n $(eval echo \$$var) ]] && printf "\e[1;4m%s\e[0m " ${var:6:1}
	done
	printf "\e[0;36m\n"
	for var in BPshowColour BPshowAddresses BPshowDate BPshowTime BPshowKernel BPshowHistNo BPshowOS BPshowUptime BPshowRAM BPshowPath
	do
		[[ -n $(eval echo \$$var) ]] && printf "%s " $(eval echo \$$var)
	done
	printf "\e[0m\n"
fi

The above script can be set to be executable and if someone runs it they will get a message telling them to source it instead. If it is sourced without any parameters, it displays the current prompt settings. If you use . prompt help it will give a help message.

.bashrc

If you place the above files in global locations, then all you need in your .bashrc file is:

. /etc/profile

If you place the above in your personal home directory (i.e., only for yourself, not affecting other users) then you can do something like this in your .bashrc:

. $HOME/bin/z-bash-prompt.sh

If you are using a personal $HOME/bin directory then you may wish to add this to your PATH, e.g.:

[[ $PATH =~ $HOME/bin ]] || export PATH=$PATH:$HOME/bin

Aside from that you will put the variables for the prompt settings, but this can be managed using the prompt script, e.g.,:

. prompt all
. prompt save

Controlling the dynamically adjustable prompt

Now that you have placed the above files installed you need only set certain environment variables to control the look of your prompt. For machines with a lot of users this would let you place the prompt settings in /etc/profile.d/ and yet allow each person to control their own prompt as they wish.

You can instantly change your BASH prompt by just setting a variable, e.g, typing the following would immediately cause your prompt to have colour:

BPshowColour=1

The list of variables that control the prompt are in the following table.

Variable	Values	Meaning
BPshowColour	0=no, 1=yes	Use colour in the prompt
BPshowAddresses	0=no, 1=yes, 2=+use	Show this machine's IP addresses. If set to 2 it will can also show this machine's purpose, such as Production or Development.
BPshowTime	0=no, 1=yes	Show date and time at the right-hand margin
BPshowKernel	0=no, 1=yes	Show the kernel version at the right-hand margin
BPshowHistNo	0=no, 1=yes	Show the command history number at each prompt
BPshowOS	0=no, 1=yes	Show the O/S version, e.g., “Gentoo” or “Oracle Linux”
BPshowUptime	0=no, 1=yes	Show up-time
BPshowPath	0=shortest, 1=standard, 2=full	Path display can be the shortest possible name (just the last component), the standard name that uses a tilde (~) to represent the HOME directory, or the full path at all times.

To conveniently set those variables and save/update the preferred settings in the user's ~/.bashrc file you can place the following script in the /usr/local/bin/ directory and then just call it with . prompt <setting> any time you want to use it.

I think this is absolutely the best BASH prompt I've ever seen anywhere, and I hope it will be useful to others as well.

Static method

The first method I had presented here set the PS1 prompt and used BASH's built-in dynamic variables, rather than using the PROMPT_COMMAND method above. It is here for reference and for those who might already be using PROMPT_COMMAND for something else, or those who are using this in a Windows BASH emulator that runs the dynamic prompt too slowly (e.g., in MINGW64 I have seen it takes 3~4 seconds to draw the prompt, which ruins the benefit).

Show/Hide static PS1 method

Here is a sample of a useful and colourful BASH prompt. I save this code as /etc/profile.d/bash-prompt.sh so it will be automatically sourced at log-in time.¹⁾

#!/bin/bash
# BASH enhancements     Angelo Babudro    ispltd.org
# Set a colourful & helpful command prompt
#
# Soft dependencies:
# - colours.sh -- ANSI terminal escape sequence definitions
# - server-details -- a file where you place code to set the variable 'purpose'
#           to show the use for a server (e.g., "Production Web", "Staging", etc.)

test -s /usr/local/bin/colours.sh && source /usr/local/bin/colours.sh
test -s /etc/profile.d/colours && source /etc/profile.d/colours

purpose=""
test -s /etc/server-details && . /etc/server-details

RootColour=$"\e[00;30;46m";          #|What colour to use to highlight that user is root?
Machine="${White}${bg_Blue}"         #|What colour to use for the machine name?

this_ip=""
ifconfig_bin="/sbin/ifconfig"
if [ -e /usr/bin/whereis ]
then
   [ -e /sbin/ifconfig ] || ifconfig_bin=`whereis ifconfig | awk '{print $2}'`
   [ -z "$ifconfig_bin" ] && ifconfig_bin="/sbin/ifconfig"
fi
if [ -s $ifconfig_bin ]
then
   this_ip=`/sbin/ifconfig | /bin/grep "inet " | /bin/grep -m1 --invert-match 127.0.0.1 | cut -f2 -d: | cut -f1 -d" "`
   this_ip="${Yellow}${purpose} ${fn}${Reset} ${this_ip}"
else
   this_ip=`ipconfig | /bin/grep -m1 "IPv4 " | cut -d: -f2`
fi
if [[ ${EUID} == 0 ]]; then
   PS1="\n\[${RootColour}\]r0oT!\[${Reset}\] \[${Machine}\]\H\[${Grey}\] ${this_ip} \[${Blue}\](\D{%a %Y-%m-%d %H:%M:%S %Z})\n\[${Yellow}\] \w\n\[${White}\]\\$ \[${Reset}\]"
else
   PS1="\n\[${Olive}\]\u\[${Grey}\]@\[${Machine}\]\h\[${Grey}\] ${this_ip} \[${Blue}\](\D{%a %Y-%m-%d %H:%M:%S %Z})\n\[${Yellow}\] \w\n\[${White}\]\\$ \[${Reset}\]"
fi
export PS1

unset Orange Olive Yellow Blue Cyan White Grey Reset

# vim:ts=3:sw=3

A more complex prompt

#!/bin/bash
# BASH enhancements	Angelo Babudro	ispltd.org
# Set a colourful & helpful command prompt
#
# Dependencies:
# - colours.sh -- ANSI terminal escape sequence definitions
# - functions.bash -- collection of BASH functions
# - server-details -- a file where you place code to set the variable 'purpose'
#                     to show the use for a server (e.g., "Production Web", "UAT DB", etc.)

[[ $- != *i* ]] && return;		#|Not an interactive shell, so no point in setting the prompt.

for foo in /usr/local/bin $HOME
do
	test -s ${foo}/colours.sh && source ${foo}/colours.sh
done

MachineColour="${White}${bg_Blue}"
[[ $EUID -eq 0 ]] && UserColour=$'\[\e[01;33;44m\]' || UserColour=$'\[\e[00;33;44m\]'

thismachine=$(hostname -s)

this_ip=""
ifconfig_bin="/bin/ifconfig"
[ -x $ifconfig_bin ] || ifconfig_bin="/sbin/ifconfig"
if [ -x /usr/bin/whereis ] && [ ! -x $ifconfig_bin ]
then
	[ -e $ifconfig_bin ] || ifconfig_bin=`whereis ifconfig | awk '{print $2}'`
	[ -z "$ifconfig_bin" ] && ifconfig_bin="ifconfig"
fi
if [ -x $ifconfig_bin ]
then
	this_ip=$($ifconfig_bin|/bin/grep -Eo "inet( | addr:)[0-9]+.[0-9]+.[0-9]+.[0-9]+"|/bin/grep -v "127.0.0.1"|/bin/sed -r 's/inet( | addr:)//'|tr '\n' ' ')
else
	this_ip="(address not found)"
fi

echo -en "\nGathering server details"
#__________[Machine purpose]___________
purpose=""
specs=""
aliases=""
if [ -x ${mybin}/bin/server-details ]
then
   IFS=$(printf "\t")
   let k=0
   for bits in $(${mybin}/bin/server-details)
   do
      [ $k -eq 0 ] && purpose="$bits"
      [ $k -eq 1 ] && location="$bits"
      [ $k -eq 2 ] && specs="$bits"
      ((k++))
   done
   IFS=$(printf "\t\n ")
else
   #___________[Machine specs]____________
	cores=""
	CPUs=1
	if [ -e "/proc/cpuinfo" ]; then
		CPUs=$(cat /proc/cpuinfo |/bin/grep -E "physical id"|sort -u|wc -l)
		cores=$(trim $(cat /proc/cpuinfo|/bin/grep "core id"|sort -u|wc -l))
	#	cores=$(trim $(cat /proc/cpuinfo |/bin/grep -E "cores"|sort -u|cut -d: -f2))
	fi
	test -e "/usr/bin/kstat" && cores=`kstat -p :::state | grep cpu_info | wc -l`
	if [ -n "$cores" ]; then
		let cores=cores*CPUs;															#|Remove any spaces
		cores="${cores}-core";															#|Make it understandable
	fi

	if [ `uname` = "SunOS" ]
	then
		fmem=`/usr/sbin/prtconf | grep Mem | awk '{print $3}'`;				#|Megabytes
		fGB="${fmem}MB"
	else
		fmem=$(free | grep Mem | awk '{print $2}');								#|Kilobytes
		fGB=$(echo "scale=1; ${fmem}/1024/1024" | bc -q 2>/dev/null);		#|Gigabytes
		fGB="${fGB}GB"
	fi
   #______________[Location]______________
#   specs="\[\e[1;35m\] ${location}\[\e[1;33m\] ${cores} ${fGB}\[\e[0m\]"
   specs="$location ${cores} ${fGB}"
fi
sayOK
echo -en "\nSetting environment"

tmuxtitle=$(set_tmux_title $thismachine)
tmuxtitle="${tmuxtitle}\\";                           #|Command ends "\" so need 2nd or it'll escape next char
[ -n $SH_LEVEL ] && gterm="\[\e]0;\h\a\]";            #|set gterm title:  \e]0; + the title + \a
# KDE Konsole uses same \e]0;(text)\a as gterm.  Just change the settings to enable "Set tab to match window title".
if [ "$TERM" = "screen" ] || [ -n "$TMUX" ]
then
	[ "$TERM" != "xterm" ] && gterm="\[${tmuxtitle}\]";
fi
[ "$TERM" = "linux" ] && gterm=""

[[ $EUID -eq 0 ]] && MyUser=" ro0T " || MyUser=${USER}
short_hist=$(basename $HISTFILE)
short_hist="H:${short_hist#*ory_}"
kern=$(uname -r); kern="K:${kern%%-*}"
tabit() {
	case $1 in
		1)	printf "\e[%dC" $(expr $(tput cols) - 15 - 27);;
		2)	printf "\e[%dC" $(expr $(tput cols) - ${#specs});;
		3)	printf "\e[%dC" $(expr $(tput cols) - 15 - ${#short_hist});;
		4)	printf "\e[%dC" $(expr $(tput cols) - ${#kern});;
	esac
}
tcols=$(tput cols)
let tab1b=tcols-${#specs}
let tab2a=tcols-15-${#short_hist}
let tab2b=tcols-${#kern}
uptime_string() {
	uptime -p|sed -r 's/ year[s]?,/y/; s/ month[s]?,/M/; s/ week[s]?,/w/; s/ day[s]?,/d/; s/ hours,/h/; s/ minutes/m/;'
}

PS1="${gterm}\n\[\$(tabit 1)${Green}\]\D{%a %d-%b-%Y %H:%M:%S %Z}\r\[$(tabit 2)${Cyan}\]${specs}\[${Reset}\]\r${MachineColour}${thismachine}${Cyan} ${aliases}${this_ip} ${purpose} \$(uptime_string)\n\[$(tabit 3)$Brown\]$short_hist ${Cyan}\r$(tabit 4)$kern\[${Yellow}\]\r \$(truepath)\n ${UserColour}${MyUser}\[${Reset}\]  "
if [[ ${EUID} == 0 ]]; then
	PS1="${PS1}\## "
else
	PS1="${PS1}\#$ "
fi
export PS1
MYSQL_PS1="${MachineColour}\h${Reset} ${Cyan}\w \R:\m:\s  ${Yellow}\d${Cyan}  \c${Reset}| "
export MYSQL_PS1

# vim:ts=3:sw=3

Mixed O/S Variation

In a mixed O/S environment where there are Linux, Solaris, and possibly AIX, etc. machines I made a modification of the above that shows the O/S and some data about the machine. Here is the PS1 setting to replace in the above:

if [[ ${EUID} == 0 ]]; then
   PS1="\n\[${Olive}\]`uname` \[${Machine}\]\H\[${Green}\] ${this_ip} \[${Title}\]\D{%a %d-%b-%Y %H:%M:%S}\[${Reset}\]\n \w\n\[${RootColour}\]« r0oT »\[${Reset}\] \## "
else
   PS1="\n\[${Olive}\]`uname` \[${Machine}\]\h\[${Green}\] ${this_ip} \[${Blue}\]\D{%a %d-%b-%Y %H:%M:%S})\[${Reset}\]\n \w\n\u $ "
fi

Here is an example of a server-details file, which is referenced in the above .bashrc script:

#!/bin/bash
# vim: ts=3 sw=3:
#
# This script determines the names of a server and some basic details
# The details are stored in the variable 'purpose' so that they can
# be used in the PS1 prompt.  Designed to handle Linux & Solaris.
# Angelo Babudro

trim() {                                                          #|Remove leading and trailing space
  [ "${purpose:0:1}" == " " ] && purpose=${purpose:1}             #|- remove leading space
  let plen=${#purpose};                                           #|- length of purpose less one
  ((plen--))
  [ "${purpose:$plen:1}" == " " ] && purpose=${purpose:0:$plen}   #|- remove trailing space
}

SVR=`/bin/hostname`
#NAMES=`command which would give me aliases for this box`
purpose=""
for FOO in ${NAMES} ${IPADD}; do
  if [[ "${SVR}" != "${FOO}" ]]
  then
    purpose="${FOO} $purpose"
  fi
  done

[ -n "$purpose" ] && trim

# Add extra details.  We could put a list of all hosts here if we have a
# small network and don't have a DB somewhere that we can query to get this data.

[ "$SVR" = "box01c02n03" ] && purpose="${purpose} MySpecialPurpose"
[ -n "$purpose" ] && trim

cores=""
test -e "/proc/cpuinfo" && cores=`cat /proc/cpuinfo | grep processor | wc -l`
test -e "/usr/bin/kstat" && cores=`kstat -p :::state | grep cpu_info | wc -l`
let cores=cores*1;                                                #|Remove leading spaces
cores="${cores}-core"

if [ `uname` = "SunOS" ]
then
  fmem=`/usr/sbin/prtconf | grep Mem | awk '{print $3}'`;         #|Megabytes
  fGB="${fmem}MB"
else
  fmem=$(free | grep Mem | awk '{print $2}');                     #|Kilobytes
  fGB=$(echo "scale=1; ${fmem}/1024/1024" | bc -q 2>/dev/null);   #|Gigabytes
  fGB="${fGB}GB"
fi

purpose="${purpose}\e[0;33m ${cores} ${fGB}"

¹⁾

You will probably need to remove any PS1 settings in files such as /etc/bashrc, /etc/bash.bashrc, or /etc/profile since they often set PS1 after the files in /etc/profile.d/ are run.

Make a colour BASH prompt

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