Mac - every command outputs 'Process completed'

Question

(2009 MacBook Pro running Snow Leopard — OS X 10.6.8)

I believe this is related to installing MacPorts today — although the other thing I did before I noticed any symptoms was install a trial of Adobe Illustrator CS6.

Initial signs were opening an extra tab in Terminal (I already had a couple open & working) — rather than give me a prompt, it just says [Process exited - exit code 1].

Things I've tried:

• Trashing Terminal prefs in ~/Library/Preferences/
• Changing 'Shell opens with' in Terminal prefs to (variously) /usr/bin/login, /bin/bash, /bin/sh
• Using Shell > New Command in Terminal to run these, and experimenting with the --norc and --noprofile switches
• Uninstalling MacPorts by following their instructions
• Restoring the backup of my .bash_profile created by MacPorts, sanity checking the contents of .bash_profile and .bashrc
• Logging off and back on again
• Restarting the Mac
• Logging in as another existing user and trying to start Terminal - same symptoms
• Attempting to run essentially anything under /bin - e.g. cat, chmod, cp, ls etc - the output is usually [Process completed] or [Process exited - exit code 1]
• Running Repair Permissions in Disk Utility
• Using safe boot mode (hold down shift at startup)

There doesn't seem to be anything especially relevant in Console Log. Note: I have Homebrew installed.

This page describes a script that'll (if it's not too old) tell me what files have been changed in Time Machine - except running that — whichever folder it's in — produces the same message.

Answer (see below): Caused by file in /usr/lib/ I'd previously replaced. Fixed once restored from backup.

Answer 1

I'm enough of a Unix nut that if I were you, I'd probably boot my machine off of a different drive so I could get a working shell and start spelunking around looking for the culprit.

But if you just want to get things working again, I'd recommend reinstalling Snow Leopard in-place. This essentially does a repair install. Make sure you have a good, full, tested backup first anyway, just in case.

By the way, don't just look in the Console log; also look in the "Kernel" and "System" and "All Messages" log streams in Console.app. The log named "Console" is usually just a log of output from processes run by the current user, not system-level processes and kernel events. You need to look in those other logs to see if there are clues at the system level.

Answer 2

This was actually due to another recent change, where I'd seen repeated advice to replace a file in /usr/lib (libcurl.4.dylib) with a newer version from some website. Fortunately I'd made a note of this and had a backup. The error was in the Console, but only it seemed during boot, it didn't complain after that.

The moment I replaced the file everything started working again.