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I'm new to OS X. I'm running OS X Lion on a MacBook Pro. Is it safe to upgrade the bash shell using Homebrew:

$ brew install bash

If safe, how do I make it the default instance of the shell I run through Terminal?

Thanks!

Jason Salaz
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Rudy
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4 Answers4

119

Binaries in /{,usr/}{,s}bin/ should not usually be replaced with other files. Other programs expect them to be the versions that came with OS X, and they are replaced by OS upgrades.

After running brew install bash, you can change the default shell safely by:

  • Adding /usr/local/bin/bash to /etc/shells
  • Running chsh -s /usr/local/bin/bash.

Settings in Terminal or iTerm 2 don't normally have to be changed. Both of them default to opening new windows with a login shell of the default shell.

The default shell can also be changed from System Preferences or with dscl, but all three options just modify /var/db/dslocal/nodes/Default/users/$USER.plist.

Lri
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Daniel
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8

I could be wrong here, but as far as I know brew would install it's own instance of bash, since brew works under /usr/local/bin while the system defaults works under /bin (and /usr/bin).

About Terminal, you can make shells open with your own, custom command. Go to Preferences > Startup and select Shells open with: Command (complete path). Simply type the path to your new bash and vuala!

Hope it helps!

BTW: Backup! Best advice in this situations!

Timo Tijhof
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kevin9794
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2

Well before you do anything, back up your current file (of course, but always deserves to be said)

sudo cp /bin/bash /bin/bash.3.2.bk

Then create a symlink to the bash executable that Homebrew downloaded. I think it will be in /usr/local/Cellar, like so

sudo ln -s /usr/local/Cellar/bash/4.2.10/bin/bash /bin/bash

Now /bin/bash points to the file in your usr/local directory

lemonginger
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    The downside of plopping a new bash in for the system version is any update of the OS can erase your preferred shell. Presumably the OP wants to use new features which could break if the OS installs a "newer than old OS" but "older than custom" version of bash. Better to change the default path or change the user shell variable. – bmike Sep 09 '11 at 22:58
  • well, you could just create a new simlink since it wouldn't overwrite the version of bash in your usr/local directory. but you are correct, Daniel's way is prob better – lemonginger Sep 09 '11 at 23:36
  • Ooh - edit your answer please to put that first (and keep the original idea if you prefer as a second alternative - I like that much better and would love a chance to reverse my vote :-) – bmike Sep 09 '11 at 23:38
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    hmm, well that /is/ what I said, but I edited to try to clarify what each step does a little better. Still think top rated answer is prob better though :) – lemonginger Sep 09 '11 at 23:44
  • This seems like a pretty dangerous way to go about changing the system shell. – Samuel Mikel Bowles Sep 10 '11 at 00:26
  • why? it can be reversed at any time. – lemonginger Sep 10 '11 at 17:15
  • If you do this, you should really point to the version-independent /usr/local/opt/bash/bin/bash instead of the versioned Cellar path. – Tim Smith Sep 26 '14 at 15:28
0

I think it is safe if you just launch

brew install bash

and then add it as your default shell

chsh -s /usr/local/bin/bash

since you are only modifying your current user. However, I noticed that my default ~/.profile is

if [ "/bin/bash" == $BASH ]; then
    source ~/.bashrc
fi

so it needs to be updated. I changed it to

if [ "bash" == $(basename $BASH) ]; then
        source ~/.bashrc
fi
Gianluca Casati
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  • See other answers for why chsh alone is not enough. Also it your updated .profile snippet looks identical to the original one – nohillside Mar 07 '16 at 09:26
  • @patrix: thanks to point it out, I updated the second snippet. It would be nice if brew install bash would not require any further action. With the updated profile I shared, it does not. I hope this can help others. – Gianluca Casati Mar 08 '16 at 08:51