117

I want to run a script to simply change the current working directory:

#!/bin/bash
cd web/www/project

But, after I run it, the current pwd remains unchanged! How can I do that?

0

11 Answers 11

142

It is an expected behavior. The script is run in a subshell, and cannot change the parent shell working directory. Its effects are lost when it finishes.

To change the current shell's directory permanently you should use the source command, also aliased simply as ., which runs a script in the current shell environment instead of a sub shell.

The following commands are identical:

. script

or

source script
9
  • 11
    @Sony: Note that you should use return to escape from a script sourced in this way, not exit - they are like shell functions, and exit will exit the shell that sourced the script. Dec 19, 2011 at 8:19
  • @CharlesStewart In fact, I'm not familiar with sourced scripts. Thank you! Dec 19, 2011 at 12:56
  • 8
    is source ./script the same?
    – amyassin
    Dec 19, 2011 at 13:04
  • 3
    @amyassin: yes, it is
    – enzotib
    Dec 19, 2011 at 13:05
  • 5
    1. . and source are equal in bash. 2. we don't need to use ./ before filename if it's in the same directory. It is ok to run only this: . script
    – sobi3ch
    Jun 16, 2016 at 15:02
53

For small tasks such as this, instead of creating script, create an alias like this,

$ alias cdproj='cd /dir/web/www/proj'

You should add this to your .bashrc file, if you want it set for every interactive shell.

Now you can run this as $ cdproj.

2
  • 1
    You can also have the script echo the commands to be executed, and then use eval `./script` or eval $(./script) to execute those commands. This is a common approach for commands that need to update the invoking shell's environment. Dec 20, 2011 at 10:41
  • 2
    Just be very careful about what you output if you are going to go the eval approach.
    – jw013
    Sep 14, 2012 at 20:08
36

Use exec bash at the end

A bash script operates on its current environment or on that of its children, but never on its parent environment.

However, this question often gets asked because one wants to be left at the bash prompt in a certain directory after the execution of a bash script from another directory.

If this is the case, simply execute a child bash instance at the end of the script:

#!/usr/bin/env bash
cd desired/directory
exec bash

This creates a new subshell. Type Ctrl+D or exit to return to the first shell where the script was initially started.

UPDATE: Use $SHELL at the end

At least with newer versions of bash, the exec on the last line is no longer required. Furthermore, the script can be made to work with whatever preferred shell by using the $SHELL environment variable. This then gives:

#!/usr/bin/env bash
cd desired/directory
$SHELL
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  • 2
    Better to just source the script, as in accepted answer: using exec is typically considered the last resort of a scoundrel.. :)
    – neuronet
    Aug 16, 2016 at 0:18
  • 1
    this trick doesn't work in debian 9 stretch.
    – vdegenne
    May 5, 2018 at 0:41
  • 6
    This is the wrong way to go about this! Mar 15, 2019 at 22:04
  • 9
    Since nobody has detailed the problems with this (I’m looking at you, @Dennis): (1) Each time you run this, it creates a new, persistent bash process. Do it ten or twenty times in a session, and you’ll have 11 to 21 bash processes piled up. This may affect performance, and, if you try to terminate the session cleanly by typing exit (or Ctrl+D), you’ll have to do that 11 to 21 times. (2) Another drawback of using an executable script is that, if you set any shell options (e.g., dotglob or globstar) in your interactive shell session, you will lose them, because you’re starting a new shell. Apr 10, 2019 at 16:39
  • 1
    Very nice solution! I've rewritten my alias in bash_profile so now it is a script stored in a separate file. I use the script to go to a newly created temporary folder. And now it is even easier to have a temporary bash session. SRP in action! Thanks! Oct 18, 2019 at 13:46
19

Depends on what you're going to do, another solution can be creating a function instead of a script.

Example:

Create a function in a file, let's say /home/aidin/my-cd-script:

function my-cd() {
  cd /to/my/path
}

Then include it in your bashrc or zshrc file:

# Somewhere in rc file
source /home/aidin/my-cd-script

Now you can use it like a command:

$ my-cd
11

While there are answers that do the exact action that you want, a more standard method for such purpose is to create symbolic link:

ln -s ~/web/www/project proj   #use full path to dir!

Then you could cd to the directory using the name proj:

cd proj

This method is more flexible because you could access files using the short name without cd:

ls proj/   #note the endslash!
vim proj/file.x
4

If you change between directories far away in the filesystem. I will recommend autojump.

0
2

Because I functionalized a lot my cd, i did this :
added this line in ~/.bashrc

alias cd='. my_cd'

and my_cd is a script in my $PATH that does the actual cd.
To prevent recusive calls an actual cd in the script is written \cd this means "uses legacy cd not the alias".

By functionalized i mean

  1. jump to the home dir of an existing project just cd to its code.
  2. just cd in a project subdir brings me to the project home dir, not my home.
  3. cd to a project inexistent (project name have nomenclature): suggest to create the environement of the project.
  4. cd to a project that hapen to be archived : ask to revive it or just move to archive.

otherwise works like cd.

1

For me the most convenient and flexible approach was a mixture of an alias and a script:

create script with arbitrary logic

Here I create a script that changes to a directory and activates the appropriate python environment. The scripts location is exmplary in /path/to/workon_myproj.sh.

#!/usr/bin/env bash

cd $HOME/workspace/myproj
source .venv/bin/activate

create alias that sources script

alias workon_myproj='source /path/to/workon_myproj.sh'

Add the alias definition into your appropriate shell start file e.g. .profile, .bashrc or .zshrc.

outcome

You can now simply execute workon_myproj in a shell which will source the content of your script in the desired directory.

extensibility

You could event improve your script to take an argument so that it works with multiple projects in a specific working directory, or combine it with a git pull to get the latest changes immediately and so on... everything boiler plate stuff you do when continuing to work on a specific project.

-1

This combines the answer by Serge with an unrelated answer by David. It changes the directory, and then instead of forcing a bash shell, it launches the user's default shell. It however requires both getent and /etc/passwd to detect the default shell.

#!/usr/bin/env bash
cd desired/directory
USER_SHELL=$(getent passwd <USER> | cut -d : -f 7)
$USER_SHELL

Of course this still has the same deficiency of creating a nested shell.

-2

You can do that using a function or using && The examples bellow installs Zabbix and creates a file with a line inside it.

Ex:

#!/bin/bash

# Create Function:
installZabbix(){
    cd /usr/src/zabbix-4.2.4;
    ./configure --enable-agent;
    make install;
    cd /usr/src/;
    >file;
    echo "Hi, this is a file." >>file;
}

# Call the function:
installZabbix

or:

#!/bin/bash
cd /usr/src/zabbix-4.2.4 && ./configure --enable-agent && make install && cd /usr/src && >file && echo "Hi, this is a file." >>file
-2

Why not use "exec" it seams to do exactly what I wish.

#!/bin/bash

cd someplace
exec bash

~/someplace
4
  • 6
    Beware of things that seem to be what you want.  (A giant wooden horse!  Just what I wanted!)  Each time you run this, it creates a new, persistent bash process.  Do it ten or twenty times in a session, and you’ll have 11 to 21 bash processes stacked up.  This may affect performance, and, if you try to terminate the session cleanly by typing exit (or Ctrl+D), you’ll have to do that 11 to 21 times. Apr 8, 2019 at 4:23
  • I could definitely see where that would be a problem. For me though I'm using it one time, doing the work I need and then exiting.If that's the only drawback I can live with that. On the other hand if there is a better solution, I'm willing to look at it.
    – paul
    Apr 10, 2019 at 14:48
  • Aidin’s answer to this question, using a shell function, and Sachin Divekar’s answer, using an alias, are (IMO) better solutions than using a script.  P.S. Another drawback of using a script is that, if you set any shell options (e.g., dotglob or globstar), you will lose them, because you’re starting a new shell. … (Cont’d) Apr 10, 2019 at 16:05
  • (Cont’d) …  P.P.S.  I just noticed that you are, basically, reiterating Serge Stroobandt’s answer and saying ‘‘Why not do this?’’  At Stack Exchange we expect answers to provide new ideas and/or information, and not just discuss other answers. Apr 10, 2019 at 16:05

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