[Info-vax] Hard links on VMS ODS5 disks

[Steven Schweda]

> [...] For example, gzip, gunzip, zcat, and gzcat, are all the
> same file, but do different things based on argv[0].

   Common in the past, but the GNU folks decided against that scheme
some time ago.  (At least a dozen years?)  For example:

proa$ pwd
/usr/local/gnu/gzip/gzip-1.12

proa$ ls -li gzip gunzip zcat
133419312 -r-xr-xr-x  1 sms  wheel    2346 Jul 12 17:21 gunzip
133419311 -rwxr-xr-x  1 sms  wheel  140108 Jul 12 17:21 gzip
133419314 -r-xr-xr-x  1 sms  wheel    1984 Jul 12 17:21 zcat

   "gunzip" and "zcat" are now shell scripts.  Excerpt from gzip.c:

[...]
#ifndef GNU_STANDARD
# define GNU_STANDARD 1
#endif
#if !GNU_STANDARD
    /* For compatibility with old compress, use program name as an option.
     * Unless you compile with -DGNU_STANDARD=0, this program will behave as
     * gzip even if it is invoked under the name gunzip or zcat.
     *
     * Systems which do not support links can still use -d or -dc.
     * Ignore an .exe extension for MSDOS and OS/2.
     */
    if (strncmp (program_name, "un",  2) == 0     /* ungzip, uncompress */
        || strncmp (program_name, "gun", 3) == 0) /* gunzip */
        decompress = 1;
    else if (strequ (program_name + 1, "cat")     /* zcat, pcat, gcat */
             || strequ (program_name, "gzcat"))   /* gzcat */
        decompress = to_stdout = 1;
#endif
[...]