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Echo not displaying variable in If-Else condition

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Top Forums Shell Programming and Scripting Echo not displaying variable in If-Else condition
# 8  
Old 02-22-2013
Brilliant, Don! I didn't see that x7, took it for $7 (although suspected an empty variable). Soooo - x_oug being the empty string which is -ne "0" yielding the output as posted!
# 9  
Old 02-22-2013
Hello Friends

Thank you so much for your quick help

I got the issue

In the following line

Code:
cat /u01/zopepx/vmstat1.txt|grep -v kthr|grep -v '-'|grep -v r|awk '{print $8}'|grep -Ev '(#.*$)|(^$)'|grep -v System|awk '{if($1>mx)mx=$1;}END{print mx}'

the logic upto following part is fine
Code:
cat /u01/zopepx/vmstat1.txt|grep -v kthr|grep -v '-'|grep -v r|awk '{print $8}'|grep -Ev '(#.*$)|(^$)'|grep -v System|

till this point we are getting values as
Code:
0
0
0

and when logic is applied over it to get MAX as following, to my surprise it is giving us MAX of 3 zeros as NULL
Code:
awk '{if($1>mx)mx=$1;}END{print mx}'

Regards
Chetanz

---------- Post updated at 07:30 AM ---------- Previous update was at 07:19 AM ----------

Hello

The results in previous post can be checked as following
Code:
#> cat >tst.txt
0
0
0
 #> awk '{if($1>mx)mx=$1;}END{print mx}' <tst.txt

Now change values in tst.txt and run following

Code:
 #> awk '{if($1>mx)mx=$1;}END{print mx}' <tst.txt


Now that the error is found, the problem is not solved .. how to get max of multiple 0 values?

Regards
Chetanz
# 10  
Old 02-22-2013
Quote:
Originally Posted by Chetanz
... ... ...
---------- Post updated at 07:30 AM ---------- Previous update was at 07:19 AM ----------

Hello

The results in previous post can be checked as following
Code:
#> cat >tst.txt
0
0
0
 #> awk '{if($1>mx)mx=$1;}END{print mx}' <tst.txt

Now change values in tst.txt and run following

Code:
 #> awk '{if($1>mx)mx=$1;}END{print mx}' <tst.txt


Now that the error is found, the problem is not solved .. how to get max of multiple 0 values?

Regards
Chetanz
Try:
Code:
printf "%d\n" 0 0 0|awk 'mx==""||$1>mx{mx=$1}END{print mx}'

# 11  
Old 02-22-2013
Clear and efficient is a BEGIN section - the loop section stays small:
Code:
awk 'BEGIN {mx=0} $1>mx {mx=$1} END {print mx}'

In this case you can also do a cast to integer by a +0:
Code:
awk '$1>mx {mx=$1} END {print mx+0}'

Last edited by MadeInGermany; 02-22-2013 at 09:27 AM..
# 12  
Old 02-22-2013
Quote:
Originally Posted by MadeInGermany
Clear and efficient is a BEGIN section - the loop section stays small:
Code:
awk 'BEGIN {mx=0} $1>mx {mx=$1} END {print mx}'

In this case you can also do a cast to integer by a +0:
Code:
awk '$1>mx {mx=$1} END {print mx+0}'

Probably not an issue for this thread, but note that neither of these will work correctly if all of the values fed into these scripts are negative.
If you try the script I suggested with negative values, such as:
Code:
printf "%d\n" -4 -1 -2|awk 'mx==""||$1>mx{mx=$1}END{print mx}'

it still works.
This User Gave Thanks to Don Cragun For This Post:
MadeInGermany
# 13  
Old 02-22-2013
Hello Don, Rudic, MadeInGermany

Thank you so much for your help

@Don - I used the snippet mentioned in your post.. it is really charming !

Regards
Chetanz
# 14  
Old 02-23-2013
Quote:
Originally Posted by Don Cragun
. . . if all of the values fed into these scripts are negative. . . .
I was thinking about sth. like initializing max to getconf INT_MINbut there may be negative REAL numbers (-1E20) so this approach wouldn't work either.
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