Re: install(1) man page

[Bob Proulx]

Rene Kapeller wrote:
> The man page says:
> 
>        -C     Install  file,  unless target already exists and is
>               the same as the new file, in which case the modifi-
>               cation time won't be changed.
> -------------------------------------------------------------------
> 'install --help'  does not mention the option '-C'
> -------------------------------------------------------------------

Interesting.  I did not previously know about this option.  But I
looked and -C is an option to the BSD install program.  Here is the
FreeBSD man page.

    -C      Copy the file.  If the target file already exists and the files
            are the same, then don't change the modification time of the
            target.  If the target's file flags and mode need not to be
            changed, the target's inode change time is also unchanged.

The GNU install program does not implement that option.  So it appears
that Red Hat added that option to their distribution for BSD
compatibility.  It appears that they patched the man page to contain
that information but did not patch the program to produce it in the
help output.  I am sure that was a simple oversight.

> ######################################
> #       on  Redhat EL 3 U4           #
> ######################################
> 
> $ rpm -qf /usr/bin/install
> coreutils-4.5.3-26
> -------------------------------------------------------------------
> $ install --version
> install (coreutils) 4.5.3
> Written by David MacKenzie.
> 
> Copyright (C) 2002 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> -------------------------------------------------------------------
> The man page does not mention the option '-C'
> -------------------------------------------------------------------
> 'install --help'  does not mention the option '-C'
> -------------------------------------------------------------------

I would guess that the patch for the option in the code still exists
but that the patch for the man page was lost in that version.  I am
sure that was not intentional since the older one had patched the man
page too.  Normally the man page is automatically generated from the
program's --help output so that they are always the same.  Something
probably simply got lost in the later packages.

Could you make a bug report to Red Hat about this?  Neither Debian nor
SuSE have patched for that option.  I did not check any others.

Note that use of install -C appears to be a non-portable option
originating in BSD.  It does not appear in SysV-like systems such as
the HP-UX one that I checked.  It appears to be a BSD-ism.  I
recommend avoiding it so that scripts using install would be portable
across systems.  The command itself is not covered by any standards
that I could find.  So we are left only with common usage as a guide.

Thanks
Bob