Bash weirdness

[Steven W. Orr]

On Thursday, Jul 24th 2008 at 13:00 -0000, quoth Tom Wittbrodt:

=>John Abreau wrote:
=>> I've got a server that's been giving strange errors lately. Most
=>> noticeably, when I login,
=>> I get several errors of the form
=>>
=>>     -bash: [: =: unary operator expected
=>>
=>>
=>>   
=>[snip]
=>> I've tried googling for these symptoms, but so far I haven't found a match.
=>> Has anyone else run across this odd behavior? What could be causing it?
=>>
=>> The server with the broken behavior is running CentOS release 5.2,
=>> and bash is bash-3.2-21.el5.
=>>   
=>
=>Any chance /bin/sh is linked to dash instead of bash?
=>
=>I had the "unary operator expected" errors on Ubuntu 6.06 until I 
=>learned they started linking /bin/sh to dash instead of bash. My CentOS 
=>systems don't seem to have dash at all but it's worth a look.
=>
=>-- Tom

Good call. I ran into this one just yesterday. Things in backquotes are 
not run by bash. They're run by /bin/sh. (I'm not sure how the SHELL 
variable plays here.) Under some Ubuntu systems, if dash is installed then 
you end up with /bin/sh symlinked to /bin/dash. You can use 

dpkg --reconfigure dash

to fix it, or use update-alternatives or galternatives.

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