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Just annotations of little "how to's", so I know I can find how to do something I've already done when I need to do it again, in case I don't remember anymore, which is not unlikely. Hopefully they can be useful to others, but I can't guarantee that it will work, or that it won't even make things worse.
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Xterm's title displaying current directory and running process, plus bash prompt also an abbreviated $PWD

Posted 08-19-2021 at 08:19 PM by the dsc
Updated 08-19-2021 at 08:41 PM by the dsc

Just found out, adapting from this answer on unix-stackexchange.

I had to adapt it somewhat because I already had "history -a" running all the time, so it would display it by default, which I don't like. Instead, the current directory would be better. So, the relevant bits of my ~/.bashrc are probably these, I think:

Code:
shopt -s histappend histreedit histverify cdspell dirspell no_empty_cmd_completion cmdhist checkwinsize autocd

# [...]

shopt -s histappend
PROMPT_COMMAND="history -a;$PROMPT_COMMAND"

# [...]

# don't put duplicate lines or lines starting with space in the history.
# See bash(1) for more options
HISTCONTROL=ignoreboth

# append to the history file, don't overwrite it
shopt -s histappend

# [...]


# this is a function that's used to "shrink" some string to a given length, which I use for $PWD, 
# and also for xterm's window title, as of now. Maybe it should be edited, removing the all-uppercase strings,
# since it brings the risk of some eventual new standard environment variable having the same name,
# and messing things up. I didn't create this function, but I've found it elsewhere, I can't remember where.

_PS1 () 
{
    local PRE= NAME="$1" LENGTH="$2";
    [[ "$NAME" != "${NAME#$HOME/}" || -z "${NAME#$HOME}" ]] &&
        PRE+='~' NAME="${NAME#$HOME}" LENGTH=$[LENGTH-1];
    ((${#NAME}>$LENGTH)) && NAME="${NAME:$[${#NAME}-LENGTH+4]}";
    echo "$PRE$NAME"
}

PS1='\u@\h:$(_PS1 "$PWD" 17)\$ '



# [...]

# and finally the actual adaptation, it just checks whether the command is "history," and if it's not, then it
# updates the title with the environment variable BASH_COMMAND appended to the shortened current directory,
# otherwise it's just the shortened PWD. It also apparently needs "sed" replacing the single-character elipsis
# for three dots, otherwise apparently it doesn't print nicely on xterm's title, at least on Openbox.
# If I could have the shortened PWD as a string, then it could be less expensively/more elegantly edited
# with endogenous string manipulation, like "${shortPWD//...}", but apparently it doesn't work like that if 
# I simply declare a string following the function itself, before PS1, the string isn't updated. Probably
# it can be set up to run along with "history -a" for every command, then it would work, I guess, haven't tried yet.
# EDIT: tried for a little while, failed miserably, it just got worse and worse the more I tried.

trap '[[ ! "${BASH_COMMAND}" == "history"* ]] && printf "\033]0;%s\007" "$(_PS1 "$PWD" 17 | sed "s||...|" )/${BASH_COMMAND//[^[:print:]]/}" || printf "\033]0;%s\007" "$(_PS1 "$PWD" 17 | sed "s||...|" )/"' DEBUG
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