On Mon, 20 Jul 2009, Mark Andrews wrote: > In message <4ad871310907191717g1ed90be7y92250f2addc38...@mail.gmail.com>, > Glen > Barber writes: > > Possibly off-topic... [..] > > > My understanding was this: > > > > > > If you specify 'sh foo.sh' at the shell, the script will be run in a > > > /bin/sh shell, _unless_ you override the shell _in_ the script. > > > > > > Ie, 'sh foo.sh' containing '#!/bin/sh' being redundant, but 'zsh > > > foo.sh' containing '#!/bin/sh' would execute using zsh. > > > > > > > > > > I meant to say in the last line: "'#!/bin/sh' would override the 'zsh' > > shel= > > l." > > > > Can someone enlighten me if I am wrong about this? > > "#!" is used to define the interpretor when the file is exec'd. > > perl, AFAIK, is the only interpretor that will look at what is after > the "#!" and modify it's behaviour. All other a interpretors (shells) > treat "#!" as a comment. > > Some shells used to examine the executable about to be called and > looked for "#!" and invoke the correct interpretor. This was how > "#!" was supported before kernels has support for "#!". It was all > done in userland.
Some rexx scripts begin with this cute trick so they may be executed in any (UNIXish) shell as 'program', or specifically as 'rexx program', where it's just a regular rexx comment: /*usr/bin/true;exec rexx -x "$0" "$@";exit# ReXX */ /* Take a measure of REXX clauses-per-second (CPS) */ /* Mike Cowlishaw (m...@ibm.com). Multi-platform. */ /* 1.0 17 Jan 89 Original version */ though I never understood why an exit would be needed after an exec .. just making sure I guess, or maybe catering for some variant or other. cheers, Ian _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
