nyerm

I jailbroke my iPhone 3G as soon as the iPhone Dev Team had posted their tool to do so, and ever since, I’ve been screwing about with the command line. There’s something deeply appealing to my inner nerd about having Unix on my phone, and recreational command line hacking is more fun for me than many of the games available for iPhone.

The one thing missing on my journey to mobile nerdvana was zsh, my favorite shell. Cydia had a zsh package available as soon as Pwnage Tool 2.0 came out, and I promptly installed it. Unfortunately, though I was able to run zsh from the command line, I couldn’t figure out how to set it as the default login shell.

Well, a bit of googling later, and I found out that on the iPhone (and possibly Mac OS X, whence iPhone derives much of its unixy goodness) editing /etc/passwd won’t do the trick. In fact, there’s a big fat comment at the head of /etc/passwd that informs you that editing it won’t be particularly useful:

# Note that this file is not consulted for login. # It only exisits for compatability with 4.3BSD utilities.

How then to set up default shells? Edit /etc/master.passwd, of course. iPhone uses this file as its authoritative user database, and changes to the login shell in this file work quite well. Change /bin/sh to /bin/zsh at the ends of the root and mobile lines, and you’re good to go. Here’s /etc/master.passwd after I’ve modified it for zsh goodness:

## # User Database # # This file is the authoritative user database. ## nobody:*:-2:-2::0:0:Unprivileged User:/var/empty:/usr/bin/false root:rootpassword:0:0::0:0:System Administrator:/var/root:/bin/zsh mobile:password:501:501::0:0:Mobile User:/var/mobile:/bin/zsh daemon:*:1:1::0:0:System Services:/var/root:/usr/bin/false _securityd:*:64:64::0:0:securityd:/var/empty:/usr/bin/false _mdnsresponder:*:65:65::0:0:mDNSResponder:/var/empty:/usr/bin/false _sshd:*:75:75::0:0:sshd Privilege separation:/var/empty:/usr/bin/false _unknown:*:99:99::0:0:Unknown User:/var/empty:/usr/bin/false

Note that you must be logged on as root to edit /etc/master.passwd.