awk conditions failing (special characters?)


 
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# 1  
Old 01-29-2015
awk conditions failing (special characters?)

This is really frustrating because I can't figure it out.

I'm running a health check script. One of the items I'm checking is the amount of memory on a server. I use the free command, which outputs something like this (excerpt)

Code:
Mem: 100 100 100 100
Swap: 100 100 100 100

In my debugging I see that $1 is "Mem:" or "Swap:" (note the ":" does come out of `free`)

My if condition is if ($1 == "Swap:") then do something

On the screen the condition matches perfectly. But to awk it does not. It never falls into that condition. What am I doing wrong? How do I build my condition so that I can check $1 for "Swap:"? Is it the colon ":" that's throwing me off?

Last edited by vgersh99; 01-29-2015 at 12:36 PM.. Reason: code tags, please!
# 2  
Old 01-29-2015
Publishing more code maybe give us more understanding.

Both rule works if input is as you have written.
Code:
# awk rule using default FS
$1 == "Swap:" { # do something
                     }
# or
{
      if ( $1 == "Swap:" ) {
             # do something
             }

}

If you processing some commands then maybe shell script is better as awk:
Code:
while read key val1 val2 val3 val4 valxxx
do
             case "$key" in
                   Swap:) #do_some 
                              ;;
                    Mem:) #do_some 
                              ;;
             esac
done < inputfile

This User Gave Thanks to kshji For This Post:
# 3  
Old 01-29-2015
$1=="Swap:" works for me.
To check, print out $1 from within awk.
Pipe the free result through hd or od -ctx1.
This User Gave Thanks to RudiC For This Post:
# 4  
Old 01-29-2015
Thanks a lot for the help!
Here's what I have. The file it's parsing is generated from an
"
Code:
free -m:|egrep 'Mem|Swap' | awk '{ print $1, $2, $3, $4} > file.out

The contents of file.out are:
Code:
Mem: 1001 800 200
Swap: 2015 98 1917

So:
Code:
awk '{
printf "$1 $2 $3 $4 are " $1 " " $2 " " $3 " " $4 "\n" #(this is my debug statement)
if ($1 == "Swap:" && $3 != 0)  # I comment out the && and it's the $1 failing for sure
  printf "WARNING - SWAP IN USE \n"
else
  some other checks which all work fine...
}' file.out >> health_check.out
cat health_check.out #another debug, actually I've got a mailx built here

Produces this:
Code:
$1 $2 $3 $4 are Mem: 1001 800 200
Output for falling through the if statement
$1 $2 $3 $4 are Swap: 2015 98 1917

same type stuff from above for falling through the else clause. Definitely not the "WARNING - SWAP IN USE" I was hoping for.

---------- Post updated at 02:17 PM ---------- Previous update was at 02:10 PM ----------

Excellent call on the od command. I forgot about that. It pans out as "Swap:", just like it's supposed to, but at least I know there's no special characters or anything else in there that might throw the condition expression off.

Last edited by Don Cragun; 01-29-2015 at 03:17 PM.. Reason: Add CODE and ICODE tags.
# 5  
Old 01-29-2015
Not the slightest idea what's happening. On my linux:
Code:
free -m | awk '/^Swap/ && $3 != 0 {print "Swap in use"}'
Swap in use

---------- Post updated at 21:47 ---------- Previous update was at 21:41 ----------

Wait a second - try to continue the line after the if (...) either with a "\" or an opening "{" or put the print right after it ...
# 6  
Old 01-29-2015
I've run into this before. For some reason my printf $4 which is the last variable on the print line did some sort of carriage return on the same line and covered up my output with the rest of the print statement. When I changed it to $3 instead or any other variable the output was fine. $4 is just a numeric like the rest, but it screwed with my output. So I changed the verbiage a little to get the same output. Perhaps the last output on the line has an embedded <CR> in it. Hey, that gives me another check with Rudi's od!
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