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From: eilts@late.e-technik.uni-erlangen.de (Hinrich Eilts)
Newsgroups: comp.unix.bsd
Subject: Re: test if file exists in script
Date: Tue, 30 Nov 1993 15:48:30 GMT
Organization: LATE, Uni-Erlangen, Germany
Message-ID: <2dfq0eEo4d@uni-erlangen.de>
References: <2deuhi$7lh@usenet.INS.CWRU.Edu>
NNTP-Posting-Host: late4.e-technik.uni-erlangen.de
Lines: 41
bx970@cleveland.Freenet.Edu (Donna A. Lilly) writes:
>What is the best way to test in a shell script (e.g. c shell or t shell if
>possible) whether a filename already exists? Given a variable file, I
>could use:
>% if (`find . -name '$file' -print | wc -c` != 0) then
> .....
>But I know there is a much better way. I also didn't have much success
>with use of
>% if (`test -s $file`) then
>also I tried the above without the backquotes, still didn't get any result
>from the test command...
It's a tricky problem, because tests in the above manner fails if
another process create the file between your test and the usage in this
process.
Try (in C-Shell notation):
set noclobber
cat "HELLO" > $file
echo $?
If $file not already exists, it will be created,
if it exists, you get an error and $? is != 0.
In sh:
#!/bin/sh
file=ttt
/bin/csh -c "set noclobber; echo $$ > $file"
echo $?
(If one know a direct way in sh, please mail it to me).
--
Bye | G i b D O S |
Hinrich Eilts | k e i n e |
(e-mail: eilts@late.e-technik.uni-erlangen.de) | C h a n c e ! |