If condition


 
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# 1  
Old 02-02-2019
If condition

hi
what is different between two code below?
what is the role of "./"?


Code:
if ( -e wind ) then

Code:
if ( -e ./wind ) then


many thanks
samad
# 2  
Old 02-02-2019
Please post (at least) OS and shell versions in every new thread that you create, so to avoid ambiguities and keep people from guessing. In above case, also the language / compiler that the construct is used for / with.

Last edited by RudiC; 02-02-2019 at 08:22 AM..
# 3  
Old 02-02-2019
my os is centos and shell is csh
above command like "if ( -e ./wind ) then" is in the shell script not language program.


thanks
# 4  
Old 02-02-2019
Please be aware that csh is not well represented nor received (for good reasons) in these fora. Even I had to search this forum's man pages. Would be worthwhile reading for you as well.



Quote:
if (expr) command If expr (an expression, as described under Expressions) evaluates true, then command is executed.
.
.
.
File inquiry operators
Some of these operators perform true/false tests on files and related objects. They are of the form -op file, where op is one of
.
.
.
e Existence
./wind explicitly denotes the current working directory to search for file "wind" whereas wind searches in the current working directory (pointed to by $PWD).

Last edited by RudiC; 02-02-2019 at 06:20 PM..
# 5  
Old 02-02-2019
Quote:
Originally Posted by RudiC
./wind explicitly denotes the current working directory to search for file "wind" whereas
We agree so far.

Quote:
Originally Posted by RudiC
wind searches in the current working directory (pointed to by $PWD).
you probably meant "searches along the PATH variable", no? In both cases, if found, the executable wind is run and the shell exits (or not exits) depending on the return code of this program.

And, yes, the best thing one can do with the csh is to forget it ever existed.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
# 6  
Old 02-02-2019
I'm afraid I hastily quoted the wrong part of the man page. I meant to copy this
Quote:
File inquiry operators
Some of these operators perform true/false tests on files and related objects. They are of the form -op file, where op is one of
.
.
.
e Existence
. I corrected my above post. Thanks bakunin for pointing this out.

Last edited by RudiC; 02-02-2019 at 06:22 PM..
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