Bash prompt (PS1) not working as intended

Question

This is my .bashrc file, I'll explain my problem in a bit.

#!/usr/bin/env bash

PS_LINE=`printf -- '  %.0s' {1..200}`

function parse_git_branch {
    PS_BRANCH=''
    PS_FILL=${PS_LINE:0:$COLUMNS}

    if [ -d .svn ] ; then
        PS_BRANCH="(svn r$(svn info|awk '/Revision/{print $2}'))"
        return

    elif [ -f _FOSSIL_ -o -f .fslckout ] ; then
        PS_BRANCH="(fossil $(fossil status|awk '/tags/{print $2}')) "
        return

    elif [ -d .hg ] ; then
        PS_BRANCH="(hg $(hg branch))"
        return
    
    fi

    ref=$(git symbolic-ref HEAD 2> /dev/null) || return
    PS_BRANCH="(git ${ref#refs/heads/}) "
}

PROMPT_COMMAND=parse_git_branch

PS_INFO="$GREEN$USER$RESET@$GREEN$HOSTNAME$RESET:$BLUE\w"
PS_VCS="$YELLOW\$PS_BRANCH"
PS_TIME="\[\033[\$((COLUMNS-10))G\] $RED[\t]"

export PS1="\${PS_FILL}\[\033[0G\]${PS_INFO} ${PS_GIT}${PS_TIME}\n${RESET}\$ "

Ok. So what I want is there's an empty line between my current directory and time (like this). As you can see, that works fine but when I restart my shell (not resource my .bashrc), it looks like this (there's no whitespace between them)

Edit

Based on @chepner answer, I got something like this

Updated code:

function parse_git_branch {
    PS_BRANCH=''
    PS_FILL=${PS_LINE:0:$COLUMNS}

    if [ -d .svn ] ; then
        PS_BRANCH="(svn r$(svn info|awk '/Revision/{print $2}'))"
        return

    elif [ -f _FOSSIL_ -o -f .fslckout ] ; then
        PS_BRANCH="(fossil $(fossil status|awk '/tags/{print $2}')) "
        return

    elif [ -d .hg ] ; then
        PS_BRANCH="(hg $(hg branch))"
        return
    
    fi

    ref=$(git symbolic-ref HEAD 2> /dev/null) || return
    PS_BRANCH="(git ${ref#refs/heads/}) "
}

function set_prompt {
    PS_INFO="$GREEN$USER$RESET@$GREEN$HOSTNAME$RESET:$BLUE\w"
    PS_VCS="$YELLOW\$PS_BRANCH"
    PS_TIME="\[\033[\$((COLUMNS-10))G\] $RED[\t]"
}

PROMPT_COMMAND=set_prompt

export PS1="\${PS_FILL}\[\033[0G\]${PS_INFO} ${PS_GIT}${PS_TIME}\n${RESET}\$ "

Typically, you set `PS1` itself in the code executed by `PROMPT_COMMAND`, not just `parse_git_branch`. — chepner, Jun 24 '21 at 14:26
@chepner wdym? You mean, I set my `PS1` in `parse_git_branch`? — KanseiKy, Jun 24 '21 at 14:27
`PS_BRANCH` may change everytime you display the prompt, but all the other variables (including `PS1`) only use the value of `PS_BRANCH` when they are first defined. — chepner, Jun 24 '21 at 14:27
Something like `PROMPT_COMMAND=set_prompt`, where `set_prompt` is a function that uses `parse_git_branch` and other code to set the value of `PS1`. — chepner, Jun 24 '21 at 14:29
@chepner Didn't quite work, you can check my updated post for details — KanseiKy, Jun 24 '21 at 14:37
No, `PS1=...` goes *inside* `set_prompt`; that's why it's called `set_prompt` and not `set_some_variables_related_to_the_prompt`. — chepner, Jun 24 '21 at 14:38
What do you mean by "restart your shell"? `.bashrc` should be automatically resourced by any new interactive shell. — chepner, Jun 24 '21 at 14:50
When my shell first run. Like exit my shell and enter it again — KanseiKy, Jun 24 '21 at 14:51
A `.bashrc` file is always sourced and never executed. Remove the shebang line. — ceving, Jun 24 '21 at 14:55
I think I should rephrased, every time I open my terminal and load my shell. The prompt become like [this](https://i.stack.imgur.com/R6bPL.png). But after I execute a single command from the CLI, (it don't matter if the command exits or not), it will load correctly (the way intended) — KanseiKy, Jun 24 '21 at 15:04

score 0 · Accepted Answer · answered Jun 25 '21 at 07:45

0

Apparently the actual number of columns in the terminal window is assigned to the COLUMNS variable only after the first prompt is issued - I could reproduce this. (It might depend on the time when a window resize signal is handled.) A not quite nice, but effective remedy is to put a delay in .bashrc - for me, sleep .2 worked. Another way is, if the number of columns of the opening terminal is known in advance, to set COLUMNS to that.

answered Jun 25 '21 at 07:45

Armali

18,255
14
57
171

Firstly, where should I put the `sleep .2`? Second, if I set the `COLLUMNS` variable, what will happen when I resize? Thanks in advance – KanseiKy Jun 25 '21 at 08:02
You can put the `sleep` anywhere in `.bashrc`. When you resize the window, the variable `COLUMNS` will be adjusted as usual. – Armali Jun 25 '21 at 08:03

Bash prompt (PS1) not working as intended

Edit

1 Answers1