Re: standards/38754: /bin/rm rm.c consistancy with other bsds

[Murray Armfield <murray%river-styx.org@localhost>]

The following reply was made to PR standards/38754; it has been noted by GNATS.

From: Murray Armfield <murray%river-styx.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: standards/38754: /bin/rm rm.c consistancy with other bsds
Date: Mon, 2 Jun 2008 16:51:22 +1000

 On Mon, 2 Jun 2008 09:05:03 am you wrote:
 > The following reply was made to PR standards/38754; it has been noted by
 > GNATS.
 >
 > From: Alan Barrett <apb%cequrux.com@localhost>
 > To: gnats-bugs%NetBSD.org@localhost
 > Cc: netbsd-bugs%NetBSD.org@localhost
 > Subject: Re: standards/38754: /bin/rm rm.c consistancy with other bsds
 > Date: Mon, 2 Jun 2008 00:00:13 +0100
 >
 >  On Mon, 26 May 2008, murray%river-styx.org@localhost wrote:
 >  > rm will display the usage message if there are no file arguments and
 >  > the -f flag is used. This does not follow POSIX. POSIX says...
 >  > "Do not write diagnostic messages or modify the exit status in the
 >  > case of nonexistent operands."
 >
 >  You seem to interpret "nonexistent operands" to mean the number of
 >  operands (not counting options such as the "-f" itself) is zero.
 >
 >  I believe that "nonexistent operands" should be interpreted to mean
 >  operands that contain strings that do not refer to entities that exist
 >  in the file system.
 >
 >  Thus, "rm -f" does not contain any "nonexistent operands"; it contains
 >  no operands at all, and "rm" should print a diagnostic message
 >  complaining about incorrect usage, and exit with an error status.
 >
 >  However, "rm -f /this/file/or/directory/does/not/exist" does contain
 >  a "nonexistent operand", and "rm" should exit without any error or
 >  diagnostic message.
 >
 >  --apb (Alan Barrett)
 
 I see your point. "Nonexistent operands" could refer to no operands, or no 
 operands that exist. The original code used the "if (argc < 1)" just as a 
 fast exit path. The addition of testing for the -f flag in the fast exit path 
 is to just drop the usage message in that case and bring rm in line with how 
 I read the standard around 'file' processing. FreeBSD and OpenBSD both drop 
 the usage message if the -f flag is used. A concern here is obviously the 
 change in behaviour which may affect existing shell script, while at the same 
 time bringing rm -f behaviour in line with other BSD's. Yet to be consistant 
 with other utility programs, if no operand is given, usage is displayed.
 
 The way I was also thinking about this was from a shell scripting point of 
 view. If I have a list variable building up a list of files to remove, when I 
 pass it to rm -f, I want it to quietly do its thing. If my variable had no 
 items, I would still want it to quietly do its thing and not issue a usage 
 message and exit with non-zero.
 
 I don't know where to go from here other than to ask other people for their 
 point of view.
 
 Thanks for questioning this point.
 
 Take care,
        Murray Armfield