Unix questions - Whence Command

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Author Whence Command
amerar@iwc.net

2006-01-24, 6:23 pm


Hi All,

I see this command at the top of a script in our
establishment......what is the $0 represent??

myfile=`whence $0`

Thanks

Steve Foley

2006-01-24, 6:23 pm

$0 is the command used to invoke the script.

If the same script is linked to foo and foobar, this will tell you which one
you picked.



<amerar@iwc.net> wrote in message
news:1138119068.159497.232760@g44g2000cwa.googlegroups.com...
>
> Hi All,
>
> I see this command at the top of a script in our
> establishment......what is the $0 represent??
>
> myfile=`whence $0`
>
> Thanks
>



amerar@iwc.net

2006-01-24, 6:23 pm


So, what do these lines prove???

myfile=`whence $0`
mypath=`dirname $myfile`

Steve Foley

2006-01-24, 6:23 pm

what does the whence command do?


<amerar@iwc.net> wrote in message
news:1138120422.459703.212860@g49g2000cwa.googlegroups.com...
>
> So, what do these lines prove???
>
> myfile=`whence $0`
> mypath=`dirname $myfile`
>



Bill Marcum

2006-01-24, 8:56 pm

On Tue, 24 Jan 2006 16:58:51 GMT, Steve Foley
<steve.foley@DELETE.att.net> wrote:
> what does the whence command do?
>

What does the man command do?
Whence may be a builtin command. Try "type whence" and, if it is
builtin, read the man page for your shell.


--
.... Logically incoherent, semantically incomprehensible, and legally ...
impeccable!
Steve Foley

2006-01-25, 2:58 am

I've got a DG/UX system, and a Linux/Mandrake 10.1. Neither has a whence
command or builtin.


"Bill Marcum" <bmarcum@iglou.com> wrote in message
news:s9sia3-1uu.ln1@don.localnet...
> On Tue, 24 Jan 2006 16:58:51 GMT, Steve Foley
> <steve.foley@DELETE.att.net> wrote:
> What does the man command do?
> Whence may be a builtin command. Try "type whence" and, if it is
> builtin, read the man page for your shell.
>
>
> --
> ... Logically incoherent, semantically incomprehensible, and legally ...
> impeccable!



Aawara Chowdhury

2006-01-25, 2:58 am

In <fhCBf.292825$qk4.4577@bgtnsc05-news.ops.worldnet.att.net>,
Steve Foley <steve.foley@DELETEatt.net> wrote:

> I've got a DG/UX system, and a Linux/Mandrake 10.1. Neither has a whence
> command or builtin.
>


Use the Korn shell on either, and you'll have a whence command (its a ksh
builtin).

AC
--
In America, through pressure of conformity, there is freedom of choice,
but nothing to choose from - Peter Ustinov.
Stephane CHAZELAS

2006-01-25, 2:58 am

2006-01-25, 03:30(+00), Steve Foley:
> I've got a DG/UX system, and a Linux/Mandrake 10.1. Neither has a whence
> command or builtin.

[...]

It's a builtin in ksh and zsh, and does the same job as "type" but
with many options and a different syntax.

See the useful "whence -m <pattern>" in zsh to search for
commands with a pattern.

$ whence -apm '?sh'
/bin/ash
/usr/bin/ssh
/usr/bin/bsh
/usr/bin/ksh
/usr/bin/zsh
/bin/csh
/usr/bin/rsh

In zsh, "type" is "whence -v", "where" is "whence -ca", "which"
is "whence -c".

--
Stéphane
Steve Foley

2006-01-29, 9:31 pm

myfile is would be the fully qualified name of your script.

mypath is the fully qualified name of the directory where your script was
invoked from.



<amerar@iwc.net> wrote in message
news:1138120422.459703.212860@g49g2000cwa.googlegroups.com...
>
> So, what do these lines prove???
>
> myfile=`whence $0`
> mypath=`dirname $myfile`
>



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