On Fri, 2011-05-27 at 14:57 -0600, Bob Proulx wrote: > Jacoby Hickerson wrote: > > Although, I am curious, is this is a matter of sh being continually > > updated to exclude all bash extensions or perhaps previously bash > > didn't interpret #!/bin/sh to be the POSIX compliant interpreter? > > When bash is invoked as sh then bash complies with the POSIX sh. That > is both required and desired. > > On some GNU/Linux systems /bin/sh is a symlink to /bin/bash and bash > will support running as a POSIX sh. But this isn't universal. On > other systems /bin/sh is an actual native POSIX sh, on others it is a > symlink to /bin/ksh or /bin/zsh or /bin/dash or others. But in all > cases /bin/sh is supposed to be a POSIX sh and conform to the > standard. Bash tries to be compliant but some differences will creep > in regardless. Doing so may cause problems for people who unknowingly > use features on one system that are not available on other systems. > Generally the wisdom of years is not to be generous in what you accept > but to be strict in what you accept. It makes portability easier. > > Having found that the bash specific feature isn't available in /bin/sh > this is a good thing for you since now your script will either need to > specify that it needs bash explicitly or you could use portable only > constructs and continue to use /bin/sh. Personally I use bash for my > command line but /bin/sh and portable constructs for shell scripts. > > Bob > Yes in this environment it is a link. It certainly makes sense to write it in a POSIX compliant way in order to be portable, but some extended features of bash make life easier. Since this was an upgrade from a previous distro Fedora 14 -> Fedora 15, I didn't think portability with a shell script would be an issue, but now it is much more clear after I have been bitten :). Your response is very excellent information and thanks to you all for the wealth of data.
Thanks! Jacoby
