while -h

[MarkSyder]

Hi everybody.

I'm just debugging a shell script (that I didn't write) and it contains a line:

while -h $PRG

I can't find any reference to -h in any of my books or in a manual page. 10 points to the first person who tells me what -h means in this context. Further points to anyone who can tell me which manual page I will find it in.

Mark Syder (like the drink but spelt different)

[Pete Randall · Accepted solution]

Mark,

ksh has a -h (but I don't think this is what you're looking for):

"-h Each command becomes a tracked alias when first encountered."

sh-posix has the same definition. Curious!


Pete

[Tom Danzig]

Assuming POSIX shell:

-h file True, if file exists and is a symbolic link.

[MarkSyder]

Thanks Pete and Tom.

Looking at the rest of the while loop, I think Tom's answer is the one that applies in this case. The script makes a lot more sense now.

Mark

[Peter Godron]

Mark,
the -h is actually part of a test.
see man test for the full spec.
Regards

[MarkSyder]

Thanks Peter.

Six points for telling me which manual page to look at.

This thread can now be considered closed.

Mark

[Gerhard Roets]

Hi Mark

You do not need to concider a thread closed anymore. Look on the page and you will see a close thread button ;)

That will stop people like me replying after the fact :P

Gerhard

[MarkSyder]

Hi Gerhard.

Please see http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=793765 - this thread persuaded me that the "close thread" feature is a bad thing that should be avoided (and preferably removed).

Mark

[Jdamian]

I'm sorry but I understand nothing about this thread.

-h is used to test when condition is enclosed in (single or double) square brackets.

while [ -h $PRG ]

or

while [[ -h $PRG ]]

For me, an expression as

while -h $PRG

means '-h' is a command.
I've written down a script using this line and the error message is:

-h: not found

[Gerhard Roets]

Hi Mark

Missed that one, I do agree with your thought process :)

Gerhard

[Elmar P. Kolkman]

I agree with J Damien... while checks the result of the command you give next, in your case -h, while normally you do something like:
while [ -h $PRG ]

meaning '[' is the command being run. And '[' is linked to the test command.

So it seems you have:
1) a special shell, having a different while command
2) an alias for while (while="while test" or something like that, though I cannot get this to work)
3) an alias for -h (-h="test -h" (this works: alias -- -h="test -h")

Or some variant on these...