On Thursday, January 15, 2004, at 02:12 PM, John Delacour wrote:
At 12:57 pm +0100 15/1/04, Stephan Hochhaus wrote:
is the file /usr/bin/perl just a link to /usr/bin/perl5.8.1 and could
therefore easily replaced by /usr/local/bin/perl5.8.2 (as an
example)? Or would that break anything?
Provided you install the later version in Apple's default location,
/usr/bin/perl will be overwritten with perl 5.8.2, 5.8.3 or whatever
and will be identical to the latest installation. This is how things
look in my directory:
-rwxr-xr-x 2 root wheel987340 8 Jan 19:47 perl
-rwxr-xr-x 1 root wheel987076 9 Nov 13:56 perl5.8.1
-rwxr-xr-x 1 root wheel 21924 18 Nov 10:14 perl5.8.2
-rwxr-xr-x 2 root wheel987340 8 Jan 19:47 perl5.8.3
John: overwritten is the wrong term here, linked would be better -
your 'perl' and 'perl5.8.3' files are linked to the same inode. That's
why they have a 2 in the first numerical column, while the other two
files have a 1. Here's an excerpt from `man ls`:
If the -l option is given, the following information is displayed
for
each file: file mode, number of links, owner name, group name,
number of
bytes in the file, abbreviated month, day-of-month file was last
modi-
fied, hour file last modified, minute file last modified, and the
path-
name.
Stephan: there's no way to tell a hard link from a regular file,
because creating a hard link to an existing file simply creates an
additional way to access the existing file's inode through a different
name. After creating the link, the original file and the new file have
equal status, neither is subordinate to the other anymore. To see
whether two files point to the same inode, you can do `ls -i`.
This is all in contrast to soft links, i.e. symbolic links, which
point by name to the original file, and remain subordinate to it. If
you deleted the original file, a hard link would work fine but a soft
link wouldn't work anymore.
-Ken
