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First character of variable

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# 1  
Old 05-06-2014
First character of variable
I am trying to detect 'nan' (not a number) string in my large txt file filled with lots of numbers. A file may have no or many 'nan'. It should be simple but getting errors. Any help appreciated. Here is what I have:

Code:
#!/bin/tcsh

set case1 = test0.txt
set chk = `grep 'nan' $case1`
set op = `$?`
if ($op == 0) then
     echo "no nan found"
else
    echo "nan found"
endif

Whatever is the file containing 'nan' or not, it always outputs "nan found"

Thank you.
# 2  
Old 05-06-2014
grep command returns zero when it match the pattern and non zero when it does not match the pattern:
Code:
EXIT STATUS

The following exit values are returned:
0         One or more lines were selected.
1         No lines were selected.
>1        An error occurred.

Last edited by Yoda; 05-06-2014 at 07:24 PM..
This User Gave Thanks to Yoda For This Post:
Anu108
# 3  
Old 05-06-2014
try something like:
Code:
#!/bin/tcsh
 set case1 = test0.txt
set nan=1
grep -q "nan" $case1 || set nan=0
if ( $nan == 0 ) then
     echo "no nan found"
else
    echo "nan found"
endif

This User Gave Thanks to rdrtx1 For This Post:
Anu108
# 4  
Old 05-07-2014
Why not use 'regular' return codes?
Code:
#!/bin/tcsh
set case1 = test0.txt
set search = nan

# Search value & set retval
grep -q "$search" "$case1"
set RET = $?

# Print result
if ( 0 == $RET ) then	
	echo "$RET - $search found"
else
	echo "$RET - $search not found"
endif

hth

EDIT:
By regular return value i mean:
Code:
EXPRESION || set nan=0

This will change the variable to zero (success) on fail, which is quite irritating when someone later has/will edit the script.

Code:
grep -q "$search" "$case1"
set RET = $?

This will set the return code always to what it was.

Also this way you could catch the error of a non existing file..
Example:
Code:
✔ ~ $ tcsh
grep: test0.txt: No such file or directory
2 - nan not found
2 ~ $ touch test0.txt
:) ~ $ tcsh
1 - nan not found
✘ ~ $ echo nan > test0.txt 
+ ~ $ tcsh
0 - nan found
✔ ~ $

Last edited by sea; 05-07-2014 at 10:18 AM..
This User Gave Thanks to sea For This Post:
Anu108
# 5  
Old 05-07-2014
First character of variable
Thank you all of the replies. Very helpful. Ended up using rdrtx1's solution.

Thank you.
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