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Re: /bin/sh -> bash compatibility?



On Fri, 2006-10-13 at 10:09 -0400, Brian Long wrote:
Hello,

I'm wondering if someone can confirm that bash runs in some sort of
Bourne Shell compatibility mode when run as /bin/sh.  When I run the
following script with #!/bin/sh, it fails.  When I run it with
#!/bin/bash, it works.  /bin/sh is a symlink to /bin/bash.

Yes, the man-page can confirm it...

       If bash is invoked with the name sh, it  tries  to  mimic  the  startup
       behavior  of  historical  versions  of sh as closely as possible, while
       conforming to the POSIX standard as well.  When invoked as an  interac-
       tive  login  shell, or a non-interactive shell with the --login option,
       it first attempts to read and execute commands  from  /etc/profile  and
       ~/.profile,  in  that  order.   The  --noprofile  option may be used to
       inhibit this behavior.  When invoked as an interactive shell  with  the
       name  sh,  bash  looks for the variable ENV, expands its value if it is
       defined, and uses the expanded value as the name of a file to read  and
       execute.  Since a shell invoked as sh does not attempt to read and exe-
       cute commands from any other startup files, the --rcfile option has  no
       effect.   A  non-interactive  shell  invoked  with the name sh does not
       attempt to read any other startup files.   When  invoked  as  sh,  bash
       enters posix mode after the startup files are read.



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