How can I shortern my command line prompt's current directory?

Question

I am using Ubuntu and I am tired of this long prompts in bash when I am working with some deep directory hierarchy. So, I would like to tweak my PS1 to shorten the working d

Answer 1

Not so different from previous solutions. However, maybe a bit more readable/editable. However, no solution to the folder name boundary, only focusing on the length of the prompt.

### SET MY PROMPT ###
if [ -n "$PS1" ]; then
    # A temporary variable to contain our prompt command
    NEW_PROMPT_COMMAND='
        pwd_short=${PWD/#$HOME/\~};
        if [ ${#pwd_short} -gt 53 ]; then
            TRIMMED_PWD=${pwd_short: 0: 25}...${pwd_short: -25}
        else
            TRIMMED_PWD=${pwd_short}
        fi
    '

    # If there's an existing prompt command, let's not 
    # clobber it
    if [ -n "$PROMPT_COMMAND" ]; then
        PROMPT_COMMAND="$PROMPT_COMMAND;$NEW_PROMPT_COMMAND"
    else
        PROMPT_COMMAND="$NEW_PROMPT_COMMAND"
    fi

    # We're done with our temporary variable
    unset NEW_PROMPT_COMMAND

    # Set PS1 with our new variable
    # \h - hostname, \u - username
    PS1='\u@\h: $TRIMMED_PWD\$ '
fi

added to the .bashrc file. All parts of the prompt is updated properly. The first part is shortened if you're in your home directory. Example:

user@computer: ~/misc/projs/solardrivers...src/com/mycompany/handles$

Answer 2

For people looking for a much simpler solution and don't need the name of the first directory in the path, Bash has built-in support for this using the PROMPT_DIRTRIM variable. From the documentation:

PROMPT_DIRTRIM

If set to a number greater than zero, the value is used as the number of trailing directory components to retain when expanding the \w and \W prompt string escapes (see Printing a Prompt). Characters removed are replaced with an ellipsis.

For example:

~$ mkdir -p a/b/c/d/e/f
~$ cd a/b/c/d/e/f
~/a/b/c/d/e/f$ export PROMPT_DIRTRIM=2
~/.../e/f$ PROMPT_DIRTRIM=3
~/.../d/e/f$ 

Downside: It depends on the directory level, not the length of the path, which you might not want.

Upside: It's very simple. Just add export PROMPT_DIRTRIM=2 to your .bashrc.

Answer 3

Apart from the bash-builtin solution using PROMPT_DIRTRIM, you may want to try $(pwd | tail -c16), which is a tad simpler than most other answers, but just gives the last 16 characters of the current directory. Of course replace 16 by any number you want.

Answer 4

echo -n $PWD | sed -re "s|(~?/[^/]*/).*(.{$pwd_length})|\1...\2|"

sed with -r only for convenience, allows to omit backslash before parentheses, and "|" as delimiter only for convenience too - because we want to use the slash inside the command. I guess your home get's displayed as ~ as well, so ~/foo/bar/baz/ should end in ~/foo/.../baz, and /foo/bar/baz/ as /foo/.../baz/.

So we take an optional ~, followed by slash, name, slash as \1, then something, then the rest as \2.

Answer 5

Why not just use ${string:position:length}? You can do ${string:-$max_chars} to have the last ${max_chars} of the string.

note the negative value

Answer 6

Another approach, still using sed and awk to generate the prompt. This will convert your $HOME directory into ~, show you your root directory, your lowest level (current directory), and its parent, separated by .. for each directory in between.

Inside of your .bashrc (or .bash_profile on OS X):

function generate_pwd {
  pwd | sed s.$HOME.~.g | awk -F"/" '
  BEGIN { ORS="/" }
  END {
  for (i=1; i<= NF; i++) {
      if ((i == 1 && $1 != "") || i == NF-1 || i == NF) {
        print $i
      }
      else if (i == 1 && $1 == "") {
        print "/"$2
        i++
      }
      else {
        print ".."
      }
    }
  }'
}
export PS1="\$(generate_pwd) -> "

The script uses awk's built in NF variable (number of fields) and positional variables ($1, $2 ...) to print each field (directory name) separated by the ORS variable (output record separator). It collapses the inner directories into .. in your prompt.

Example of it in use:

~/ -> cd Documents/
~/Documents/ -> cd scripts/
~/Documents/scripts/ -> cd test1/
~/../scripts/test1/ -> cd test2
~/../../test1/test2/ -> pwd
/Users/Brandon/Documents/scripts/test1/test2
~/../../test1/test2/ -> cd test3/
~/../../../test2/test3/ -> cd test4/
~/../../../../test3/test4/ -> pwd
/Users/Brandon/Documents/scripts/test1/test2/test3/test4
~/../../../../test3/test4/ -> cd /usr/
/usr/ -> cd local/
/usr/local/ -> cd etc/
/usr/local/etc/ -> cd openssl/
/usr/../etc/openssl/ -> cd private/
/usr/../../openssl/private/ ->