#! gotcha

[Dave Sill]

I ran into a good one yesterday.  A shell script was, for some reason,
running under a restricted shell depending upon whether the file name
of the script contained an 'r'.  This only occurred when the script
was run directly; typing `sh bar' worked fine.

It turns out the Bourne shell looks for an 'r' anywhere in argv[0] and
runs restricted if it finds one.  Well, that seems ok.  After all, we
don't usually rename the shell.

Unfortunately, when #! magic is used to specify the shell, argv[0]
becomes the name of the shell script.

I don't know how widespread this problem is.  On our 4.2 BSD system
the code that looks for 'r's in argv[0] is commented out.  It got me
on a 4.1c BSD system.

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The opinions expressed above are mine.

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