topic Re: tar command options in Operating System - HP-UX

tar command options

dictum9 — Wed, 20 Sep 2006 14:49:11 GMT

Why does the syntax for tar different from syntax for every other hpux command?

Case in point, you are supposed to say
tar xvf
and not
tar -xvf

Every other command precedes its option or switches with "-", for example rm, cp, find and more.

I've always said

tar -xvf
and
tar -cvf
without any problems.

Re: tar command options

James R. Ferguson — Wed, 20 Sep 2006 14:54:22 GMT

Hi:

You can use either:

# tar -xvf

(or):

# tar -xvf

Personally, I use the "-" character to denote the switch that the options that follow represent.

The best answer I can provide to your question of why the "-" is optional is that 'tar' is one very old utility; written when conformity and standards were less rigorously enforced or valued.

Regards!

...JRF...

Re: tar command options

Arunvijai_4 — Wed, 20 Sep 2006 14:58:19 GMT

Hi,

You can both of them "tar tvf" or tar -tvf. I am not sure why other commands doesn't allow you to do this.

-Arun

Re: tar command options

Pupil_1 — Wed, 20 Sep 2006 15:05:15 GMT

# tar
tar: usage tar [-]{txruc}[eONvVwAfblhm{op}][0-7[lmh]] [tapefile] [blocksize] [[-C directory] file] ...
#

There is the "-" in the syntax and since the command works very well without the "-" give me more flexibility !!

As JRF said, most people are used to typing
tar -cvf or tar -xvf ...

Re: tar command options

Ivan Ferreira — Wed, 20 Sep 2006 15:40:00 GMT

Normally if you use the "-" way, you must specify the argument for the option right after the option, for example, these commands are equivalent:

tar -cvf /dev/rmt/0m -b 1024 /

tar cvfb /dev/rmt/0m 1024 /

Re: tar command options

Bill Hassell — Wed, 20 Sep 2006 16:55:14 GMT

tar is extremely old (decades) and it's command line design defines the first item is the key. The - is optional but it is not like any other command where -tvf is the same as -t -v -f. Also, the file you specify may be optionally followed by -C directory, again non-standard. The man page explains this.

tar's only use is for simple exchanges of data. It is inappropriate for full system backups or large system backups.

Re: tar command options

Peter Nikitka — Thu, 21 Sep 2006 01:33:06 GMT

Hi,

as a remark to Bill's answer:
If you have a real heterogenous environment and must exchange backup files between them, 'tar' is nearly unbeatable as backup backend utility, IMHO.

mfG Peter