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Full Discussion: use of hyphen in #! line
Top Forums Shell Programming and Scripting use of hyphen in #! line Post 302112554 by Dhruva on Thursday 29th of March 2007 01:27:50 AM
Old 03-29-2007
Thank you all for the interest.What i found is this is something related with the security and prevent some kind of spoofing attacks(mainly with sid).
The text posted below is from the link posted by Perderabo.
Quote:
sh -
or by:
#! usr/bin/sh -
the historical systems have assumed that no option letters follow. Thus, this volume of IEEE Std 1003.1-2001 allows the single hyphen to mark the end of the options, in addition to the use of the regular "--" argument, because it was considered that the older practice was so pervasive. An alternative approach is taken by the KornShell, where real and effective user/group IDs must match for an interactive shell; this behavior is specifically allowed by this volume of IEEE Std 1003.1-2001.

Note:
There are other problems with set-user-ID scripts that the two approaches described here do not resolve.
But still i am not able to understand what is it.I would appreciate if somebody can explain it in simple language.
 

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LEARN ABOUT SUNOS

shells

shells(4)							   File Formats 							 shells(4)

NAME

       shells - shell database

SYNOPSIS

       /etc/shells

DESCRIPTION

       The shells file contains a list of the shells on the system. Applications use this file to determine whether a shell is valid. See getuser-
       shell(3C). For each shell a single line should be present, consisting of the shell's path, relative to root.

       A hash mark (#) indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by  the  routines
       which search the file. Blank lines are also ignored.

       The  following  default	shells are used by utilities: /bin/bash, /bin/csh, /bin/jsh, /bin/ksh, /bin/pfcsh, /bin/pfksh, /bin/pfsh, /bin/sh,
       /bin/tcsh,  /bin/zsh,  /sbin/jsh,  /sbin/sh,  /usr/bin/bash,  /usr/bin/csh,  /usr/bin/jsh,  /usr/bin/ksh,  /usr/bin/pfcsh,  /usr/bin/pfksh,
       /usr/bin/pfsh, and /usr/bin/sh, /usr/bin/tcsh, /usr/bin/zsh. Note that /etc/shells overrides the default list.

       Invalid shells in /etc/shells may cause unexpected behavior (such as being unable to log in by way of ftp(1)).

FILES

       /etc/shells	       lists shells on system

SEE ALSO

       vipw(1B), ftpd(1M), sendmail(1M), getusershell(3C), aliases(4)

SunOS 5.10							    4 Jun 2001								 shells(4)
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