On 03/19/2012 02:15 PM, Stefano Lattarini wrote: > On 03/19/2012 08:54 PM, Lane Schwartz wrote: >> Hi, >> >> If I have a file that contains a bash script, is there any >> straightforward way of determining whether that script can be parsed >> successfully as a Bash script, without actually running the file? >> > Yes: the "-n" option. Simple examples: > > $ echo 'if :; then echo not seen; fi' | bash -n; echo status: $? > status: 0 > $ echo 'if :; then echo not seen' | bash -n; echo status: $? > bash: line 2: syntax error: unexpected end of file > status: 2
Support for -n is required by POSIX for all sh-like shells. But it comes with some caveats - on Solaris 8, the implementation of '/bin/sh -n' is extremely inefficient, and can take several minutes on complex scripts. And even older, on SunOS 4, you could make '/bin/sh -n' go into an infinite loop on a script as simple a while loop that never executes. More recently, modern ksh '-n' warns about every suspicious construct, such as complaining about `` instead of $(). And don't ever try 'set -n' in an interactive script or in the middle of a shell, as you can't use 'set +n' to turn it back off :) -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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