Question

In my .bashrc, I got this:

PS1="[\w $]"

And every time when I cd to a dir with a deep level, the shell prompt almost takes up the whole line, (terminal size: 80*24), like:

[/level_a_dir/level_b_dir/level_c_dir/level_d_dir/level_e_dir $]

Question

I want to cut the prompt short if the pwd is longer than 20 chars, just keep the last dir, like:

[.../level_e_dir $]
#[/level_a_dir/level_b_dir/level_c_dir/level_d_dir] is replaced with ...

How to do it?

Answer 1

I have done it in the following way.
First you have to create a shell script, truncate.sh:

#!/bin/bash
MAXLEN=20
REPLACEMENT="..."

# replace /home/user by ~
TPWD=$(echo ${PWD} | sed 's#'${HOME}'#~#;')

# truncate
if [ ${#TPWD} -gt ${MAXLEN} ] ; then
  PWDOFFSET=$(( ${#TPWD} - ${MAXLEN} ))
  TPWD="${REPLACEMENT}${TPWD:${PWDOFFSET}:${MAXLEN}}"
fi

echo ${TPWD}

Next you have to replace your PS1:

export PS1="[\$(truncate.sh) ] "