Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: My for loop decides to become an infinite loop?
Top Forums Shell Programming and Scripting My for loop decides to become an infinite loop? Post 302580703 by Corona688 on Friday 9th of December 2011 10:22:49 AM
Old 12-09-2011
Quote:
Originally Posted by gotreef
It looks like your little script snippit solved all my problems plus I feel like I've learned a lot as well, for which I'm greatful.

One quick thing though. When you have the "while read FILE", how does it know that the FILE is the /tmp/$$ file?
Glad it worked for you.

It doesn't -- it just reads from standard input. But the </tmp/$$ tells it what "standard input" is supposed to be, at the bottom of the loop.

Imagine it like this:
Code:
read FILE </tmp/$$

...except that there's an entire loop involved:
Code:
while read FILE
do
...
done </tmp/$$

...in which the file gets opened once and put into standard input for read and anything else inside the loop to read as it pleases.

You can do that, in shell -- redirect the input and/or output of entire loops and statements:

Code:
# all 5 echo statements go into the same file
for N in 1 2 3 4 5
do
        echo $N
done > output

 

10 More Discussions You Might Find Interesting

1. Solaris

ls command in infinite Loop

Hi, whenever I am giving a 'ls' command system is going into infinite loop displaying the current home directory. There is no separate shell script/file with ls name anywhere in the system. I am using Solaris 10. Any help / guidance in solving this problem is highly appreciated. ... (3 Replies)
Discussion started by: umakant
3 Replies

2. Shell Programming and Scripting

Infinite loop not looping

Hi guys, I'm having a problem getting my infinite loop to loop. It simply reads in the users choice form the menu, executes the corresponding case statement and quits instead of looping back to the main menu again. I have a feeling it might be something with my if then statements within the case... (2 Replies)
Discussion started by: hootdocta5
2 Replies

3. Programming

Is my code in an Infinite Loop?

Production C code compiled without the dash-g option is running, and seems to be in an infinite loop. Is there a way to tell? Is there a diagnostic tool that will report what objects or what lines of code or even what functions are being executed? Or is my best option to kill it with a dump? ... (5 Replies)
Discussion started by: marcus121
5 Replies

4. Shell Programming and Scripting

infinite while do loop problem

hi all, this is how my scrip looks like #!/bin/sh bindir='/opt/apps/script/bin' datadir='/opt/apps/script/data' dir='/opt/apps/script' while : ; do ls -1rt /opt/apps/script/data/check.txt*|tail -1 > /dev/null 2>&1 if ;then chmod +rwx $bindir/dummy2.sh ... (8 Replies)
Discussion started by: tententen
8 Replies

5. Shell Programming and Scripting

Infinite while loop

what is the difference between while:,while true and while false? (6 Replies)
Discussion started by: proactiveaditya
6 Replies

6. UNIX for Advanced & Expert Users

Procmail and infinite loop

I wanted to copy (not forward but copy) all incoming email to another address of mine. It worked, but now I encountered an infinite loop problem: When the second address doesn't like the content and bounces the message back, the bounce message will be sent back and forth. So, what I have in... (1 Reply)
Discussion started by: distill
1 Replies

7. Shell Programming and Scripting

Call a infinite loop

Hi All, I need to run an infinite loop. requirement below: function1 --> creates a file file1 function2 ---> need to call if the file creates i am running these both function via a script --> script.sh i need to run the function1 first and if the file file1 creates then need to run the... (3 Replies)
Discussion started by: satyaranjon
3 Replies

8. Homework & Coursework Questions

Help with infinite loop problem

1. The problem statement, all variables and given/known data: My problem is an infinite loop when i press any other key other then Y or y in the while loop. what i want it to do is return to the normal script outside of it if pressing N or n or keep asking the same question if its any other... (4 Replies)
Discussion started by: Ren_kun
4 Replies

9. Shell Programming and Scripting

How to stop infinite loop

Im unable to stop the below infinite loop (bash script). Can someone tell me why this isnt responding to signals eg: ctrl+c (SIGINT) or ctrl+z c=0 test_loop() { c=$(($c+1)) echo "count value is : $c " sleep 1 test_loop } Im using: SunOS 5.10 PS: If run this as... (13 Replies)
Discussion started by: Arun_Linux
13 Replies

10. Shell Programming and Scripting

Infinite loop query

I have a script script.shwhich is scheduled to run at 11 AM everyday. # script.sh Code: ./scb_script.sh & unfortunately scb_script.sh is running today in infinite loop as respective files are not available. My question, when script.sh starts running tomorrow, will the old process be... (1 Reply)
Discussion started by: JSKOBS
1 Replies

LEARN ABOUT NETBSD

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 04:44 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy