bash - how to pipe result from the which command to cd

Question

How could I pipe the result from a which command to cd?

This is what I am trying to do:

which oracle | cd
cd < which oracle

But none of them works.

Is there a way to achieve this (rather than copy/paste of course)?

Edit : on second thought, this command would fail, because the destination file is NOT a folder/directory.

So I am thinking and working out a better way to get rid of the trailing "/oracle" part now (sed or awk, or even Perl) :)

Edit : Okay that's what I've got in the end:

cd `which oracle | sed 's/\/oracle//g'`

are you trying to get directory where program is installed? `dirname`, `basename `? — Anycorn, Aug 09 '10 at 05:37
@aaa : you are right, I think dirname is better because it points to "the real dir" not a symbolic link to the oracle executable...which is why my sed apporach would fail :) — Michael Mao, Aug 09 '10 at 06:01

score 134 · Accepted Answer · edited May 04 '17 at 21:26

134

You use pipe in cases where the command expects parameters from the standard input. ( More on this ).

With cd command that is not the case. The directory is the command argument. In such case, you can use command substitution. Use backticks or $(...) to evaluate the command, store it into variable..

path=`which oracle`
echo $path # just for debug
cd $path

although it can be done in a much simpler way:

cd `which oracle`

or if your path has special characters

cd "`which oracle`"

or

cd $(which oracle)

which is equivalent to backtick notation, but is recommended (backticks can be confused with apostrophes)

.. but it looks like you want:

cd $(dirname $(which oracle))

(which shows you that you can use nesting easily)

$(...) (as well as backticks) work also in double-quoted strings, which helps when the result may eventually contain spaces..

cd "$(dirname "$(which oracle)")"

(Note that both outputs require a set of double quotes.)

edited May 04 '17 at 21:26

anishpatel

1,152
1
12
22

answered Aug 09 '10 at 05:25

mykhal

16,760
11
69
76

Cool. Could you please explain a bit about what is going on here? That looks like a variable dereference; is there some default temporary variable where the results of a command go? – Nate W. Aug 09 '10 at 05:26
Ahhh, I forgot compelete about the backticks :( – Michael Mao Aug 09 '10 at 05:27
4

You need another pair of quotes: `cd "$(dirname "$(which oracle)")"`. – Philipp Aug 09 '10 at 11:05
The `|` opens a new process, so even if `cd` read from STDIN, `cmd | cd` wouldn't work (i.e. the current directory in the original process would remain the same). – Kyle Strand Apr 02 '14 at 22:35

score 25 · Answer 2 · 2017-05-05T05:33:05.077

25

With dirname to get the directory:

cd $(which oracle | xargs dirname)

EDIT: beware of paths containing spaces, see @anishpatel comment below

edited May 05 '17 at 05:33

answered Aug 09 '10 at 05:38

3

Use `cd "$(which oracle | xargs -0 dirname)"` if the path may contain whitespace. The -0 flag splits input by null rather than whitespace. – anishpatel May 04 '17 at 21:24

score 9 · Answer 3 · answered Aug 09 '10 at 05:25

9

cd `which oracle`

Note those are backticks (generally the key to the left of 1 on a US keyboard)

answered Aug 09 '10 at 05:25

Cfreak

18,362
6
44
56

1

This doesn't work if the path contains spaces or other "special" characters, and you have to strip off the file name. – Philipp Aug 09 '10 at 11:08
@Philipp you can use this if your path has special characters `cd "\`which oracle\`"` – Ram Patra Jul 09 '16 at 15:10

score 4 · Answer 4 · answered Aug 09 '10 at 11:07

4

OK, here a solution that uses correct quoting:

cd "$(dirname "$(which oracle)")"

Avoid backticks, they are less readable, and always quote process substitutions.

answered Aug 09 '10 at 11:07

Philipp

43,805
12
78
104

score 2 · Answer 5 · answered Aug 09 '10 at 10:56

You don't need a pipe, you can do what you want using Bash parameter expansion!

Further tip: use "type -P" instead of the external "which" command if you are using Bash.

# test
touch /ls
chmod +x /ls
cmd='ls'
PATH=/:$PATH
if cmdpath="$(type -P "$cmd")" && cmdpath="${cmdpath%/*}" ; then
   cd "${cmdpath:-/}" || { echo "Could not cd to: ${cmdpath:-/}"; exit 1; }
else
   echo "No such program in PATH search directories: ${cmd}"
   exit 1
fi

score 1 · Answer 6 · edited Apr 13 '17 at 12:36

1

besides good answer above, one thing needs to mention is that cd is a shell builtin, which run in the same process other than new process like ls which is a command.

edited Apr 13 '17 at 12:36

Community

1
1

answered Aug 24 '14 at 07:39

Jiacai Liu

2,260
2
16
32

score 1 · Answer 7 · answered Aug 09 '10 at 05:37

1

In response to your edited question, you can strip off the name of the command using dirname:

cd $(dirname `which oracle`)

answered Aug 09 '10 at 05:37

David Z

116,302
26
230
268

This doesn't work if the path contains spaces or other "special" characters. – Philipp Aug 09 '10 at 11:09
1

Easily fixed by double-quoting it. – David Z Aug 09 '10 at 18:25

bash - how to pipe result from the which command to cd

7 Answers7

Linked