Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Variable loses value outside loop
Top Forums Shell Programming and Scripting Variable loses value outside loop Post 303004476 by cero on Tuesday 3rd of October 2017 06:27:34 AM
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

 

10 More Discussions You Might Find Interesting

1. AIX

AIX System Loses communication

We run an RS/6000 SP Frame. One of the nodes running (AIX 5), in the frame, seems to run fine for a few weeks and then will no longer communicate with the outside world. I can not telnet to the server or ping the server. This is true for both the ethernet and serial connection. I believe what... (3 Replies)
Discussion started by: k11rh
3 Replies

2. UNIX for Dummies Questions & Answers

copy loses the text format

Hi I try to copy part of text from one file to another file. My problem is the text in the new file loses all the format. My code is: #!/bin/sh while red line do if then echo "$line" >> ./new_file else break fi done < "./old_file" Is there a way to modify... (3 Replies)
Discussion started by: tiger99
3 Replies

3. UNIX Desktop Questions & Answers

Grep result loses formatting

I am searching for a string in a file and then redirecting the contents in another file... however the formatting is not preserved.. Can you please help me on this ... (5 Replies)
Discussion started by: blackeyed
5 Replies

4. UNIX for Dummies Questions & Answers

FTP loses write permissions

Hi Guys, i have learned today that when you ftp a file with full write permissions (777) to another destination it loses the w options. so a file that was once -rwxrwxrwx(before FTP) is now -rw-r--r-- (after FTP). why does this happen? and is it configurable? Regards, (8 Replies)
Discussion started by: brian112
8 Replies

5. Shell Programming and Scripting

[SHELL: /bin/sh] For loop using variable variable names

Simple enough problem I think, I just can't seem to get it right. The below doesn't work as intended, it's just a function defined in a much larger script: CheckValues() { for field in \ Group_ID \ Group_Title \ Rule_ID \ Rule_Severity \ ... (2 Replies)
Discussion started by: Vryali
2 Replies

6. Shell Programming and Scripting

printing variable with variable suffix through loop

I have a group of variables myLINEcnt1 - myLINEcnt10. I'm trying to printout the values using a for loop. I am at the head banging stage since i'm sure it has to be a basic syntax issue that i can't figure out. For myIPgrp in 1 2 3 4 5 6 7 8 9 10; do here i want to output the value of... (4 Replies)
Discussion started by: oly_r
4 Replies

7. UNIX for Dummies Questions & Answers

Loop and variable not exactly variable: what's wrong

Hello guys, This truly is a newbie question. I'm trying to make a loop to execute simultaneous commands indefinitely while using variable. Here is how my mess looks like (this is just an example): #!/bin/bash IP=`shuf -n 1 IP.txt` # I figured this would be easier to select random lines... (4 Replies)
Discussion started by: bobylapointe
4 Replies

8. Shell Programming and Scripting

Array Variable being Assigned Values in Loop, But Gone when Loop Completes???

Hello All, Maybe I'm Missing something here but I have NOOO idea what the heck is going on with this....? I have a Variable that contains a PATTERN of what I'm considering "Illegal Characters". So what I'm doing is looping through a string containing some of these "Illegal Characters". Now... (5 Replies)
Discussion started by: mrm5102
5 Replies

9. Shell Programming and Scripting

[Solved] How to increment and add variable length numbers to a variable in a loop?

Hi All, I have a file which has hundred of records with fixed number of fields. In each record there is set of 8 characters which represent the duration of that activity. I want to sum up the duration present in all the records for a report. The problem is the duration changes per record so I... (5 Replies)
Discussion started by: danish0909
5 Replies

10. Shell Programming and Scripting

Infinite "while" loop subshell loses current date variable

I have a simple script to log network connectivity to a set of systems. However, as expected the date appended to the log never changes because the new variable is lost when the loop starts again. Can someone clue me in on how to get around this issue? #!/bin/bash LOG=/tmp/netlog... (3 Replies)
Discussion started by: woodson2
3 Replies

LEARN ABOUT MINIX

break

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]

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 man 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  vari-
           able  assignment.  This means that tilde substitution is performed after the = sign, and also that word splitting and file name genera-
           tion 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), sh( 1), attributes(5)

SunOS 5.10                                                          17 Jul 2002                                                           break(1)
All times are GMT -4. The time now is 08:58 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy