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Harley avatar Ubuntu

Can't see python virtual environment name in bash prompt when PROMPT_COMMAND is being used to modify PS1

bt flag
Harley

I shortened my bash prompt by appending the following code block in ~/.bashrc file.

get_PS1(){
    local pwdmaxlen=30
    local trunc_symbol="\[$(tput setaf 1)$(tput bold)\]..."
    
    if [[ "${#PWD}" -gt "$pwdmaxlen" ]]; then
        local right_chunk="\[$(tput setaf 4)$(tput bold)\]${PWD:$((${#PWD}-$pwdmaxlen)):${#PWD}}\[$(tput sgr0)\]"
        PS1="${trunc_symbol}${right_chunk} \$ "
    else
        PS1="\[$(tput setaf 4)$(tput bold)\]\$(pwd) \$\[$(tput sgr0)\] "
    fi
}

PROMPT_COMMAND=get_PS1

When it is active, I mean after exec bash, if I create a virtual environment with virtualenv venv and subsequently activate it with source venv/bin/activate, (venv) should have shown up at the beginning of bash prompt. There's no way to understand that I'm running a virtual environment, although which python does in fact, show that I'm inside a virtual environment.

From what I understand, this happens only when I use PROMPT_COMMAND variable. It doesn't matter, what type of modification I did inside get_PS1 function, It'll always behave this way. I know the PROMPT_DIRTRIM way, but that's not what I'm looking for.

Bash version is 5.0.17(1)-release. I'm running Kubuntu 20.04.3 LTS.

By the way, I learned this code block from here.

Thanks. Let me know if any other info is required.

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Harley avatar Ubuntu
bt flag
Harley

It can be done with the assistance of VIRTUAL_ENV variable. When a virtual environment eg. env is activated, it's path is stored in VIRTUAL_ENV and can be seen with echo $VIRTUAL_ENV.

Now format, filter and store the virtual environment name with this:

local virt_env=`printf "($(echo $VIRTUAL_ENV | awk -F "/" '{print $NF}'))"`;

After that, append the virt_env variable to PS1 when required. After adding new logic the get_PS1 will look like this:

get_PS1(){
    local pwdmaxlen=30
    local trunc_symbol="\[$(tput setaf 1)$(tput bold)\]..."
    local virt_env=`printf "($(echo $VIRTUAL_ENV | awk -F "/" '{print $NF}'))"`;

    if [[ "${#PWD}" -gt "$pwdmaxlen" ]]; then
        local right_chunk="\[$(tput setaf 4)$(tput bold)\]${PWD:$((${#PWD}-$pwdmaxlen)):${#PWD}}\[$(tput sgr0)\]";
        if [[ -n "$VIRTUAL_ENV" ]]; then
            PS1="${virt_env} ${trunc_symbol}${right_chunk} \$ ";
        else
            PS1="${trunc_symbol}${right_chunk} \$ ";
        fi
    else
        if [[ -n "$VIRTUAL_ENV" ]]; then
            PS1="${virt_env} \[$(tput setaf 4)$(tput bold)\]\$(pwd) \$\[$(tput sgr0)\] ";
        else
            PS1="\[$(tput setaf 4)$(tput bold)\]\$(pwd) \$\[$(tput sgr0)\] ";
        fi
    fi
}

note: the if-else code blocks could probably be improved, but it did the job for me.

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