Login or Register to Ask a Question and Join Our Community


UNIX for Beginners Questions & Answers

If condition

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums UNIX for Beginners Questions & Answers If condition
# 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:
RudiC
# 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..
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Help with if condition

o/p of my command is given below My requirement is if Pnumber is 0 then stabilization.Build.2013 else stabilization.PBuild.2013.3 (11 Replies)
Discussion started by: nikhil jain
11 Replies

2. UNIX for Dummies Questions & Answers

IF [ condition ] help

Hi all Unix newbie - please be gentle Am modifying an existing script to error trap a variable with a length of 0 #!/bin/bash ipfile='/var/data/bin/ipaddress' ] && ipold="$(< "$ipfile" )" ipnew="$( wget -q -O - checkip.dyndns.org | sed -e 's/.*Current IP Address: //;s/<.*$//' )" #... (6 Replies)
Discussion started by: CRChamberlain
6 Replies

3. Shell Programming and Scripting

If condition return 0 even when it fails to satisfy te condition

HI My doubt may be basic one but I need to get it clarified.. When i use "if" condition that checks for many AND, OR logical conditions like if ]; then return 0 fi Even the if condition fails it returns as zero.. Any clue.. But if i add else condition like if ]; ... (2 Replies)
Discussion started by: Priya Amaresh
2 Replies

4. Shell Programming and Scripting

if condition

if chr1:109457160 1 109457160 99.1735537190083 + chr1:109457233 1 109457233 99.1735537190083 - chr1:109457614 1 109457614 99.1735537190083 + chr1:109457618 1 109457618 100 + chr1:109457943 1 109457943 100 - chr1:109458224 1 109458224 99.1735537190083 - file1.txt If 6th column in... (3 Replies)
Discussion started by: johnkim0806
3 Replies

5. Shell Programming and Scripting

redirect stdout echo command in condition A run in condition B

hi, I have some problems in my simple script about the redirect echo stdout command inside a condition. Why is the echo command inside the elif still execute in the else command Here are my simple script After check on the two diff output the echo stdout redirect is present in two diff... (3 Replies)
Discussion started by: jao_madn
3 Replies

6. HP-UX

Difference between [condition] and [[condition]] and ((condition)) when used with if condition

Executed the following if conditions .. and got different results . only (( )) gave correct o/p with all scenarios . Can anybody please let me know what is the difference between and ] and ((condition)) when used with if condition. And why each condition gave different result. 1.... (2 Replies)
Discussion started by: soumyabubun
2 Replies

7. Shell Programming and Scripting

If Condition

Hi, I am trying to execute this command, but is it not working, says "`;' unexpected" eval $lgrep $SAM_CMD ; if ; then ; echo "No Error" ; fi What i want is, return the command output, if it is non zero, say "No Error". Thanks, John. (21 Replies)
Discussion started by: john_prince
21 Replies

8. Shell Programming and Scripting

if..else condition

i have a paramter data_date in which i am passing a string value.i want to find out another paramter file_date from this.the logic is given below if day of data_date = sunday or monday then file_date=data_date-1 else file_date=data_date-2 i am passing data_date as 20061027. how can i... (3 Replies)
Discussion started by: dr46014
3 Replies

9. Shell Programming and Scripting

if condition

Hi friends, :) In a shell script i found the following if condition. echo -n "Which version of $1 do you want to restore ('0' to quit)? : " read desired if ${desired:=1} -ge $index ] ; then echo "$0: Restore canceled by user: index value too big." >&2 exit 1 fi Can... (1 Reply)
Discussion started by: ravi raj kumar
1 Replies

10. Shell Programming and Scripting

if condition ...

i have following if condition if above statement is case sensitive.....what is syntax if i have to make above comparision case insensetive (4 Replies)
Discussion started by: mahabunta
4 Replies
Login or Register to Ask a Question