Shell standardization (for c.std.unix)
C.R. Ritson
C.R.Ritson at newcastle.ac.uk
Thu Jan 17 23:34:20 AEST 1991
Submitted-by: C.R.Ritson at newcastle.ac.uk ("C.R. Ritson")
Please could you post this to comp.std.unix, or else reply to it
yourself if that is more appropriate.
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I am unsure of the state of standardisation of the unix shells, but
hope that the standards committees would consider removing a piece of
functionality that is becoming both irrelevant and dangerous.
I am thinking of the feature where, after the exec system call fails
to be able to execute a file, the shell assumes that if it has the
execute bit set and is a file, then it must be a shell script. Now
that the exec system call on most systems understands the "#!"
notation as a valid magic number and starts the named interpretor
itself, this is no longer needed, provided this behaviour itself
becomes standard.
The danger of direct interpretation by the shell is that the file is
quite likely to be an executable object file for some other
architecture seen from the wrong side of an NFS mount. When this is
the case the shell produces large numbers of "not found" messages and
often ends up resetting numerous operating modes. Our newer users
find this most confusing.
Chris Ritson
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Volume-Number: Volume 22, Number 74
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