CODEWITHSUNDEEP
bashcd
Jørgen
Jørgen

Reputation: 9130

Why can't my shell function change directory from piped input?

I have made a cli which computes the location of a certain directory, and I would really like to have the script change into it. My first approach was ./myscript | cd which I've learned doesn't work as 1. cd doesn't take piped arguments, and 2. the script won't be allowed to change the directory of the parent shell.

I learned that there are workarounds, and I tried creating a function in .bash_profile:

function cdir(){
  DIR=""
  while read LINE; do
      DIR=$LINE
  done
  echo $DIR
  cd $DIR
}

Now running ./myscript | cdir the correct directory is output, however, the directory is still not changed.

Using command substitution works: cd $(./myscript), but I'd really prefer to be able to write this using pipe. Do you have any idea how I can get this to work, or at least explain why it isn't possible?

Upvotes: 1

Views: 413

Answers (1)

codeforester
codeforester

Reputation: 42999

cd changes the current working directory, which is an attribute of the process. When you use a pipeline, shell creates a subprocess and the effect of cd (inside your function) is lost when the subprocess finishes.

cd -- "$(./myscript)"

is the right way of doing it. Here, cd runs in your current shell.

See also:

Upvotes: 3

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