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Breaking if-else loop and variety of comparisions

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Top Forums Shell Programming and Scripting Breaking if-else loop and variety of comparisions
# 1  
Old 08-31-2009
Breaking if-else loop and variety of comparisions
Hello Friends,

Im trying to write a script to invoke nagios. In order to do this I grep some words that comes from output of some backup scripts. When there is "End-of-tape detected" in directed output logs it should give alarm. First I would like to know if there is any better way to write comparision loops. Second if the alarm condition occurs in a loop there is no need to run the next loops so how can i break loops and end the script right way?

Code:
find . -name ufsdump_output1.txt | xargs egrep "End-of-tape detected" | wc -l > word_count1.txt   
###i used wc-l to detect existance of the words "End-of-tape detected" , i know i could do it with awk but coudlnt be sure###
NUM1 = cat word_count1.txt

if [ $NUM1 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"                  exit 0 
elif [ $NUM1 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

find . -name ufsdump_output2.txt | xargs egrep "End-of-tape detected" | wc -l > word_count2.txt
NUM2 = cat word_count2.txt

if [ $NUM2 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"                  exit 0 
elif [ $NUM2 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

find . -name ufsdump_output3.txt | xargs egrep "End-of-tape detected" | wc -l > word_count3.txt
NUM1 = cat word_count3.txt

if [ $NUM3 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"	            exit 0 
elif [ $NUM3 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

I'd like to find out your thoughts,
thanks by advanced
Last edited by EAGL€; 08-31-2009 at 04:38 AM.. Reason: i deleted a redundant variable in script.
# 2  
Old 08-31-2009
Hello EAGL€,

Quote:
Originally Posted by EAGL€
Second if the alarm condition occurs in a loop there is no need to run the next loops so how can i break loops and end the script right way?
Just the instruction break

Code:
NUM1 = cat word_count1.txt

Should be
Code:
NUM1=$(cat word_count.txt)

And I am sure there is a way to optimise your code. Might be worthwhile if you have many large files to process.
# 3  
Old 08-31-2009
Nope, i tried the commands and Manuel was right unfortunately so bash only allows break to be used in while and for-do loops not if-else loops. Im gonna change the loops as while.

result was
Code:
./break.sh: line 9: break: only meaningful in a `for', `while', or `until' loop

thanks anyhow..
# 4  
Old 08-31-2009
Of course. break only works on loops and if..else is a conditional structure that does not loop.
# 5  
Old 08-31-2009
I don't get why you need to break. Once the condition is evaluated the script goes on

might this be helpful
Code:
#!/bin/bash

for n in {1..3};  do
   eval NUM$n=$(egrep -R -c "End-of-tape detected" .)
   case NUM$n; in
      0) echo "TAPE HAS STILL SPACE FOR BACKUP"
         exit
      ;;
      [1-9]|[1-9]0-9]*) echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"
                        exit 2
      ;;
   esac
done

Instead of 'exit'ing, you can assign a new variable, which you could use to define other actions
# 6  
Old 08-31-2009
Quote:
Originally Posted by EAGL€
Hello Friends,

Im trying to write a script to invoke nagios. In order to do this I grep some words that comes from output of some backup scripts. When there is "End-of-tape detected" in directed output logs it should give alarm. First I would like to know if there is any better way to write comparision loops. Second if the alarm condition occurs in a loop there is no need to run the next loops so how can i break loops and end the script right way?

Code:
find . -name ufsdump_output1.txt | xargs egrep "End-of-tape detected" | wc -l > word_count1.txt   
###i used wc-l to detect existance of the words "End-of-tape detected" , i know i could do it with awk but coudlnt be sure###
NUM1 = cat word_count1.txt

if [ $NUM1 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"                  exit 0 
elif [ $NUM1 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

find . -name ufsdump_output2.txt | xargs egrep "End-of-tape detected" | wc -l > word_count2.txt
NUM2 = cat word_count2.txt

if [ $NUM2 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"                  exit 0 
elif [ $NUM2 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

find . -name ufsdump_output3.txt | xargs egrep "End-of-tape detected" | wc -l > word_count3.txt
NUM1 = cat word_count3.txt

if [ $NUM3 = 0 ]; then
echo "TAPE HAS STILL SPACE FOR BACKUP"	            exit 0 
elif [ $NUM3 != 0 ]; then
echo "ATTENTION! EOT REACHED, CHANGE CARTRIDGE!"  exit 2
fi

I'd like to find out your thoughts,
thanks by advanced
Code:
#!/usr/bin/bash

MAXIDX=3
IDX=1
DONE=1

while [ ${IDX} -le ${MAXIDX} -a ${DONE} -eq 1 ]
do
  if [ `find . -name ufsdump_output${IDX}.txt -exec grep -il "End-of-tape detected" {} \; | wc -l` -gt 0 ]
  then
     DONE=0
     echo "ATTENTION! EOT REACHED FOR INDEX ${IDX}, CHANGE CARTRIDGE!"
  fi
  ((IDX=${IDX}+1))
done



---------- Post updated at 10:07 PM ---------- Previous update was at 10:03 PM ----------

The usage of "break" in a loop is a sign of weakness, like saying "I am not able to come up with a decent solution." A loop is supposed to have a proper end condition.
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