45

Is there a way to execute a command in a different directory without having to cd to it? I know that I could simply cd in and cd out, but I'm just interested in the possibilities of forgoing the extra steps :)

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  • It's rather trivial to make a script that does this: echo "#!/bin/bash; cd $1; exec $2" > /usr/local/bin/execindirectory; chmod +x /usr/local/bin/execindirectory. Might need to put a little more effort if you want it to actually support option "tags" such as -d and stuff. – LawrenceC May 26 '11 at 2:26
  • As user-unknown states in an answer, all the examples you've given here and in comments are better addressed by other solutions, so it's unclear if there is actually a problem that needs solving here. Can you come up with a better example? – Caleb May 26 '11 at 9:43
60

I don't know if this counts, but you can make a subshell:

$ (cd /var/log && cp -- *.log ~/Desktop)

The directory is only changed for that subshell, so you avoid the work of needing to cd - afterwards.

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  • 2
    That's what I usually do. – Adam Byrtek May 26 '11 at 17:48
  • Nice, I had forgotten altogether about sub-shells, very handy in this case. – Naftuli Kay May 26 '11 at 21:02
  • 5
    To avoid potential chaos, sub out the semicolon with two ampersands: $ (cd /var/log && cp *.log ~/Desktop). That way, if the directory doesn't exist, no further commands are executed. – Naftuli Kay Apr 11 '13 at 19:38
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    Note for anyone else as naive as me: the $ at start isn't part of the command, just everything after it. – Maltronic Apr 15 '17 at 13:58
  • TNX, worked on arch/zsh. – aasmpro May 9 at 20:25
14

Some programs have options with which you can tell them to chdir(2) themselves (e.g. GNU tar’s -C/--directory).

Outside of such programs though, something will have to chdir. You could write and use some sort of compiled “binary” program instead of having the shell do it, but it probably would not yield much benefit.

In a comment in another answer, you gave an example:

execindirectory -d /var/log "cp *.log ~/Desktop"

Since the *.log pattern is expanded by the shell itself (not cp), something will have to chdir to the directory before having a shell evaluate your command.

If you are just interesting in avoiding having to “cd back”, then you can use a subshell to isolate the effect of the cd from your working shell instance.

(cd /path/to/dir && some command)

You can package this up in a shell function. (I dropped the -d option from your example usage since there is little point to this command if the directory is actually optional.)

runindir() { (cd "$1" && shift && eval "$@"); }

runindir /var/log 'cp *.log ~/Desktop'  # your example
runindir /var/log cp \*.log \~/Desktop  # eval takes multiple args

runindir /var/log cp \*.log ~/Desktop   # it is okay to expand tilde first
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  • 2
    I like this solution, except, personally I'd use pushd/popd – N J May 26 '11 at 3:57
13

Not to undermine the value of answers given by other people, but I believe what you want is this:

(cd /path/to && ./executable [ARGS])

Note the parens to invoke cd in a sub-shell.

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  • I don't think so. As I understand, he wants to end up in the initial directory. – Adam Byrtek May 26 '11 at 17:51
  • Oh, I totally forgot to wrap that into sub-shell. Corrected my answer, thank you. – alex May 26 '11 at 18:48
4

Here is something that should let you cd back where you were (using Bash), since not forgetting to do so seems to be the purpose of the question:

# Save where you are and cd to other dir
pushd /path/to/dir/that/needs/to/be/current/dir

run-your-command

# Get back where you were at the beginning.
popd

(EDIT: slightly shorter version, thanks to @Random832)

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  • 1
    you could just pushd other-dir, rather than pushd .; cd other-dir – Random832 May 26 '11 at 12:06
  • @Random832, good point! – Bruno May 26 '11 at 12:09
2

Sadly, your example:

execindirectory -d /var/log "cp *.log ~/Desktop"

doesn't need a change to the dir, because 

cp /var/log/*.log ~/Desktop

would do the same. Can't you get closer to your real problem? Because we might know a better solution for that too.

A complicated way to solve your problem, which is far away from the elegance of Michaels solution, is the usage of find, which has a switch '-execdir' to be performed in the dir, where a file is found. Badly adopted to your example: 

find /var/log -maxdepth 1 -type f -name "*.log" -execdir echo cp {} ~/Desktop ";"

Maybe it is useful for your real problem. -okdir instead of -execdir will ask you to confirm every invocation.

-okdir and -execdir might need gnu-find to be installed, which is typically used on Linux.

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1

How about ./your/path/command.sh?

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  • No, I actually meant something like the following: execindirectory -d /var/log "cp *.log ~/Desktop". – Naftuli Kay May 26 '11 at 1:23
  • I'm perfectly aware that this isn't strictly necessary, by the way, I'm just interested in if it can actually be done. – Naftuli Kay May 26 '11 at 1:24

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