Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: How do you wait for command substitution processes to complete?
Top Forums UNIX for Dummies Questions & Answers How do you wait for command substitution processes to complete? Post 302397633 by mrvwman on Monday 22nd of February 2010 07:39:34 PM
Old 02-22-2010
How do you wait for command substitution processes to complete?
When running a command using the >(cmd) syntax in bash how do you wait for the command to complete before moving on in your script?

Here is a simple example:
Code:
zcat largefile.gz | tee >(wc && echo “HELLO”) > /dev/null
# I tried wait, here but it doesn't wait for the process in the subshell.
echo "WORLD"

This produces the output:
Code:
WORLD
22245  175374 3598423
HELLO

My objective is to guarantee echo "WORLD" gets printed after all of the >() processes are done.

The bigger picture is that I have a lot of large log files to process through a variety of log parsers and using this syntax does have the positive effect of reading the files from disk once to process them in parallel in many sub processes taking advantage of multi-core CPUs. Everything works fine except for the fact that I can't tell when those processes are done.

I can think of one solution where I could have my log processing scripts write an "I'm Done" message to a file or pipe somewhere for the parent to loop listening for.

Is there a better way?
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

PERL: wait for process to complete

I'm using PERL on windows NT to try to run an extract of data. I have multiple zip files in multiple locations. I am extracting "*.t" from zip files and subsequently adding that file to one zip file so when the script is complete I should have one zip file with a whole bunch of ".t" files in it. ... (2 Replies)
Discussion started by: dangral
2 Replies

2. Shell Programming and Scripting

Wait for Background Process to complete

I am attempting within a for-loop, to have my shell script (Solaris v8 ksh) wait until a copy file command to complete before continueing. The specific code is: for files in $(<inputfile.lst) do mv directory/$files directory/$files ksh -m -i bg %% wait $! done I am shaky on the... (3 Replies)
Discussion started by: gozer13
3 Replies

3. Shell Programming and Scripting

Wait Command

Does anyone have an example of a korn shell scripts kicking of multiple background processes and then using the wait command to get the return code from those processes? I want to write a program that kicks off multiple Oracle procedures and then wait for the return code before I procede.... (1 Reply)
Discussion started by: lesstjm
1 Replies

4. Programming

Howto spawn multiple child processes and wait?

As far as I can tell, the bash wait command waits for a logical "AND" of all the child processes. Assuming I am coding in C: (1) What is the function I would use to create multiple bash child process running perl? (2) What is the function I would use to reinvent the bash wait command so I... (4 Replies)
Discussion started by: siegfried
4 Replies

5. Shell Programming and Scripting

wait command - cat it wait for not-chile process?

Did not use 'wait' yet. How I understand by now the wait works only for child processes, started background. Is there any other way to watch completion of any, not related process (at least, a process, owned by the same user?) I need to start a background process, witch will be waiting... (2 Replies)
Discussion started by: alex_5161
2 Replies

6. Filesystems, Disks and Memory

hdparm + HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl

Hi All, Am finding performance of my SD card using hdparm. hdparm -tT /dev/BlockDev0 /dev/BlockDev0: Timing cached reads: 1118 MB in 2.00 seconds = 558.61 MB/sec HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate ioctl for device Timing buffered disk reads: 14... (0 Replies)
Discussion started by: amio
0 Replies

7. Shell Programming and Scripting

Wait command help

Hi, Is there any way to know the child process status as and when it finished. If i write like below nohup sh a1.sh & ### has sleep 20 ;echo a1.sh nohup sh a2.sh & ### has sleep 10 ;echo a2.sh nohup sh a3.sh & ### has sleep 5 ;echo a3.sh wait This will wait till a1.sh ,a2.sh a3.sh... (0 Replies)
Discussion started by: patrickk
0 Replies

8. Shell Programming and Scripting

Wait for one processes to complete in a shell script

Let's say I start process A.sh, then start process B.sh. I call both of them in my C.sh How can I make sure that B starts its execution only after A.sh finishes. I have to do this in loop.Execution time of A.sh may vary everytime. It is a parameterized script. (17 Replies)
Discussion started by: rafa_fed2
17 Replies

9. Shell Programming and Scripting

In Shell Script Does Second Command Wait For First Command To Complete

Hi All, I have a question related to Shell scripting. In my shell script, I have following two commands in sequence: sed 's/^/grep "^120" /g' $ORIGCHARGEDAMTLIST|sed "s;$;| cut -f$FIELD_NO1 -d '|' | awk '{ sum+=\$1} END {printf (\"%0.2f\\\n\", sum/100)}' >$TEMPFILE mv $TEMPFILE $ORIGFILE... (3 Replies)
Discussion started by: angshuman
3 Replies

10. Shell Programming and Scripting

Bash script parallel tasks and command to wait untill complete?

Hello, im having bash script with while *** command1 && command2 && command3 && done i want to ask how i can prevent overloading server, by waiting untill all commands complete? any low resources intensive command like "wait" - i dont know if exist? (2 Replies)
Discussion started by: postcd
2 Replies

LEARN ABOUT DEBIAN

gst-complete

gst-complete-0.8(1)						   User Commands					       gst-complete-0.8(1)

NAME

       gst-complete-0.8, gst-complete - perform bash completion for gst-launch command lines

SYNOPSIS

       complete -Cgst-complete-0.8 gst-launch

       gst-complete [--gst-list-mm] [--gst-mm=string] [--print]

DESCRIPTION

       gst-complete-0.8 enables bash to provide context-sensitive tab completion for gst-launch command lines. See gst-launch(1) for the syntax of
       gst-launch command lines.

       You must have a version of bash that supports programmable completion. Such versions of bash provide the complete built-in command.

       gst-complete is a wrapper script that runs the latest installed version of gst-complete-X.X. For example, if both gst-complete-0.7 and gst-
       complete-0.8 are installed on your system, gst-complete runs gst-complete-0.8.

OPTIONS

       The following options are supported by gst-complete-0.8 and gst-complete:

       --help	       Display detailed usage message. You can also use -? to specify this option.

       The following options are supported by gst-complete only:

       --gst-list-mm   List found major/minor versions. This option displays the versions that are available.

       --gst-mm=string Force  major/minor  version.  This  option  enables you to specify a specific version to run, if you do not want to run the
		       default version.

       --print	       Print wrapped command line. This option displays the command that will be run, and then runs the command.

EXAMPLES

       Example 1: Generating the Registry of Available Plugins by Running gst-compprep

       Run the following command in your .bash_profile or other appropriate place:

       example% complete -C gst-complete-0.8 gst-launch

       Example 2: Running the Wrapper Script and Displaying the Command Name

       example% gst-complete --print
       /usr/bin/gst-complete-0.8

FILES

       The following files are used by this application:

       /usr/bin/gst-complete-0.Executable for bash completion for gst-launch

       /usr/bin/gst-complete   Wrapper script that runs the latest installed version of gst-complete-X.X

ATTRIBUTES

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

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-media		   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       gst-compprep(1), gst-feedback(1), gst-inspect(1), gst-launch(1), gst-launch-ext(1), gst-md5sum(1), gst-register(1), gst-thumbnail(1),  gst-
       typefind(1), gst-xmlinspect(1), gst-xmllaunch(1), gstreamer-properties(1), libgstreamer-0.8(3), libgstgetbits(3)

NOTES

       Original man page written by the GStreamer team at http://gstreamer.net/.

       Updated by Brian Cameron, Sun Microsystems Inc., 2004.

SunOS 5.10							    14 Oct 2004 					       gst-complete-0.8(1)
All times are GMT -4. The time now is 11:42 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy