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Variable loses value outside loop

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# 1  
Old 10-03-2017
Hammer & Screwdriver Variable loses value outside loop
Hi,

I am looking for a global variable found_flag to be set a value that can be accessed outside the loop anywhere in the bash shell script.

Code:
 more test.sh
 found_flag=0
 searchdir=/web/bea_apps/applications
  
 find . -type f \! -name tasty.tar | $AWK -F/ '{print $NF}' | while IFS= read -r entry; do
  
 found_flag=0
 find $searchdir -type f -name $entry | grep -v LOGS | while IFS= read -r second_entry; do
  
 mv $second_entry $second_entry.$NOW.bkp
 cp -R $entry `dirname $second_entry`/
 found_flag=1
 echo "Displaying the value of found_flag:$found_flag"
  
 done
  
 echo "Displaying the value of found_flag outside while loop:$found_flag"
  
 done

Output: bash -x test.sh
Code:
 
 + find . -type f '!' -name client.tar
 + /usr/xpg4/bin/awk -F/ '{print $NF}'
 + IFS=
 + read -r entry
 + found_flag=0
 + find /web/bea_apps/applications -type f -name sd.ear
 + grep -v CURRENT
 + IFS=
 + read -r second_entry
 + mv /web/bea_apps/applications/sd.ear /web/bea_apps/applications/sd.ear.10032017.bkp
 ++ dirname /web/bea_apps/applications/sd.ear
 + cp -R sd.ear /web/bea_apps/applications/
  
 + found_flag=1
 + echo 'Displaying the value of found_flag:1'
 Displaying the value of found_flag:1
 + IFS=
 + read -r second_entry
 + echo 'Displaying the value of found_flag outside while loop:0'
 Displaying the value of found_flag outside while loop:0

In the RED BOLD output above I am expecting the found_flag to have the value=1 instead of zero.

Can you please suggest a quick way how I can set the value globally so it reflects outside the loop as well ?

Using sub-shells would be my last priority.
Last edited by rbatte1; 10-03-2017 at 07:35 AM.. Reason: Converted QUOTE tags to CODE tags and removed unnecessary FONT formatting (probably pasted in)
# 2  
Old 10-03-2017
Hi,

by piping the output of find/awk/grep to the loop a subshell is created, thats why the variable in the parent shell is unchanged.
Avoid piping to the loop, bash for example offers process substitution that can be used here:
Code:
$ cat x.sh
echo piping
a=0
ls *.sh |while read i; do
   echo $i
   a=$(( a + 1 ))
   echo inside: $a
done
echo outside: $a
echo =====
echo process substitution
a=0
while read i; do
   echo $i
   a=$(( a + 1 ))
   echo inside: $a
done < <(ls *.sh)
echo outside: $a

$ ./x.sh
piping
hw.sh
inside: 1
x.sh
inside: 2
outside: 0
=====
process substitution
hw.sh
inside: 1
x.sh
inside: 2
outside: 2

# 3  
Old 10-03-2017
Try setting the lastpipe option in bash

Quote:
shopt [-pqsu] [-o] [optname ...]
Toggle the values of settings controlling optional shell behavior.
.
.
.
lastpipe
If set, and job control is not active, the shell runs the last command of a pipeline not executed in the background in the current shell environment.
I think ksh operates like this per default...
# 4  
Old 10-03-2017
I'm curious about this:

Code:
find . -type f \! -name tasty.tar | $AWK -F/ '{print $NF}' | while IFS= read -r entry; do

And then you search for $entry later ... why not just search for tasty.tar?

How about:

Code:
entry=$(find . -name 'tasty.tar' -type f)
if [ ! -f "$entry" ]
then
        echo "tasty.tar not found" >&2
        exit 1
fi

entry=$(basename "$entry")

# 5  
Old 10-04-2017
RedHat
Quote:
Originally Posted by RudiC
Try setting the lastpipe option in bash



I think ksh operates like this per default...
I m trying this option for a solution.

Code:
#!/bin/bash
shopt -s lastpipe

However, I get the below error.

Code:
./run.sh: line 2: shopt: lastpipe: invalid shell option name

My bash version is

Code:
bash-3.2$ bash --version
GNU bash, version 3.2.57(1)-release (sparc-sun-solaris2.10)
Copyright (C) 2007 Free Software Foundation, Inc.

Last edited by mohtashims; 10-04-2017 at 08:24 AM..
# 6  
Old 10-04-2017
That version of bash is 10 years old.

You could try using ksh instead.
This User Gave Thanks to Corona688 For This Post:
drl
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