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Full Discussion: Bash loops and variable scope
Top Forums UNIX for Dummies Questions & Answers Bash loops and variable scope Post 302503696 by 1skydive on Friday 11th of March 2011 02:01:22 PM
Old 03-11-2011
Bash loops and variable scope
Hi All,

I've been researching this problem and I am pretty sure that the issue is related to the while loop and the piping. There are plenty of other threads about this issue that recommend removing the pipe and using redirection. However, I haven't been able to get it working using the ssh and grep command.

Code:
#!/bin/bash
export date=`date '+%m/%d/%Y'`
ALERT=90
ADMIN=me@me.com
DIR="/tmp"
COUNT=0

function type1(){

  local host=$1
  ssh $host df -hP --exclude-type=nfs | grep -E "sd[bcd]|mapper" | grep -v VGsys | awk "{print \$5 \" \" \$1}" | while read output;
  do
    usep=$(echo $output | awk "{ print \$1}" | cut -d'%' -f1  )
    partition=$(echo $output | awk "{ print \$2 }" )
    if [ "$usep" -ge "$ALERT" ]; then
      USAGE=$(echo -e "$partition ($usep%)")
      TOTAL="$TOTAL $USAGE"
      echo $TOTAL
    fi
  done
  echo $TOTAL
  echo -e "$host\n$TOTAL\n"  >> "$DIR/servers.txt"

}

for i in server1 server2 server2; do
  type1 $i;
done


mail -s "$ALERT% Storage Report for $date" $ADMIN  < "$DIR/servers.txt"

rm "$DIR/server.txt"

As you can see, the TOTAL is available within the while loop but is then empty after the loop exits.

Any suggestions appreciated.

Thanks for you help.

---------- Post updated at 02:01 PM ---------- Previous update was at 10:35 AM ----------

Hah! So why is it, you bash (no pun intended) your head against a wall for a couple of days, trying every possible combination you can think of. No sooner you post the question, the light bulb goes off.

So, I moved the ssh command to the for loop output to a file and then used redirection for the while loop. Its not perfect, but at least I have my variables now and can work on the other issues I have.

This is what I ended up doing:

Code:
#!/bin/bash
export date=`date '+%m/%d/%Y'`
ALERT=90
ADMIN=me@me.com
DIR="/tmp"
COUNT=0

function type1(){

  local host=$1
  while read output
  do
    usep=$(echo $output | awk "{ print \$1}" | cut -d'%' -f1  )
    partition=$(echo $output | awk "{ print \$2 }" )
    if [ "$usep" -ge "$ALERT" ]; then
      USAGE=$(echo -e "$partition ($usep%)")
      TOTAL="$TOTAL$USAGE"
      echo $TOTAL
    fi
  done < "$DIR/hosts.txt"
  echo -e "$host\n$TOTAL\n"  >> "$DIR/servers.txt"

}

for i in server1 server2 server2; do
  ssh $host df -hP --exclude-type=nfs | grep -E "sd[bcd]|mapper" | grep -v VGsys | awk "{print \$5 \" \" \$1}" >> "$DIR/hosts.txt"
  type1 $i;
done


mail -s "$ALERT% Storage Report for $date" $ADMIN  < "$DIR/servers.txt"

rm "$DIR/server.txt"
rm "$DIR/hosts.txt"

Hope it helps someone else out.
 

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LEARN ABOUT OPENSOLARIS

continue

break(1)							   User Commands							  break(1)

NAME

       break, continue - shell built-in functions to escape from or advance within a controlling while, for, foreach, or until loop

SYNOPSIS

   sh
       break [n]

       continue [n]

   csh
       break

       continue

   ksh
       *break [n]

       *continue [n]

   ksh93
       +break [n]

       +continue [n]

DESCRIPTION

   sh
       The break utility exits from the enclosing for or while loop, if any. If n is specified, break n levels.

       The continue utility resumes the next iteration of the enclosing for or while loop. If n is specified, resume at the n-th enclosing loop.

   csh
       The  break  utility  resumes  execution after the end of the nearest enclosing foreach or while loop. The remaining commands on the current
       line are executed. This allows multilevel breaks to be written as a list of break commands, all on one line.

       The continue utility continues execution of the next iteration of the nearest enclosing while or foreach loop.

   ksh
       The break utility exits from the enclosed for, while, until, or select loop, if any. If n is specified,	then  break  n	levels.  If  n	is
       greater than the number of enclosing loops, the outermost enclosing loop shall be exited.

       The  continue utility resumes the next iteration of the enclosed for, while, until, or select loop. If n is specified then resume at the n-
       th enclosed loop. If n is greater than the number of enclosing loops, the outermost enclosing loop shall be used.

       On this manual page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

	   1.	  Variable assignment lists preceding the command remain in effect when the command completes.

	   2.	  I/O redirections are processed after variable assignments.

	   3.	  Errors cause a script that contains them to abort.

	   4.	  Words that follow a command preceded by ** that are in the format of a variable assignment are expanded with the same rules as a
		  variable  assignment.  This  means  that tilde substitution is performed after the = sign, and also that word splitting and file
		  name generation are not performed.

   ksh93
       break is a shell special built-in that exits the smallest enclosing for, select, while, or until loop. It also exits the nth enclosing loop
       if n is specified. Execution continues at the command following the loop or loops.

       If n is specified, it must be a positive integer >=1. If n is larger than the number of enclosing loops, the last enclosing loop is exited.

       continue  is  a	shell special built-in that continues execution at the top of the smallest enclosing for, select, while, or until loop, if
       any; or of the top of the nth enclosing loop if n is specified.

       If n is specified, it must be a positive integer >=1. If n is larger than the number of enclosing loops, the last enclosing loop is used.

       On this manual page, ksh93(1) commands that are preceded by one or two + symbols are special built-in commands and are treated the  follow-
       ing ways:

	   1.	  Variable assignment lists preceding the command remain in effect when the command completes.

	   2.	  I/O redirections are processed after variable assignments.

	   3.	  Errors cause a script that contains them to abort.

	   4.	  Built-in commands are not valid function names.

	   5.	  Words  following  a command preceded by ++ that are in the format of a variable assignment are expanded with rules as a variable
		  assignment. This means that tilde substitution is performed after the = sign and field splitting and file  name  generation  are
		  not performed.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       csh(1), exit(1), ksh(1), ksh93(1), sh(1), attributes(5)

SunOS 5.11							    8 Apr 2008								  break(1)
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