Debian Programming :: Running Programs In Parallel In Bash
Jul 22, 2014
I am trying to replicate what is happening on this page under the tcsh shell, but using the bash shell found in Wheezy. Here is the page I am referring to:[URL] The command I am trying to replicate is on page 6 under figure 2.4. The command is "prompt> ./mem &; ./mem &".
I would like to run the same program twice, concurrently, but do not know how. Note that I am not trying to use a bash script, but rather by simply using syntax on the command line.
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Oct 1, 2010
I have a bash script with a line like this in it:
Code: mysqldump -uusername -ppassword --master-data=2 --single-transaction --quick --add-drop-table --add-drop-database somedatabase | gzip > ./somedatabase.sql.gz The problem is, I have about 16 databases I'm dumping like this, but it's dumping
[Code]....
So, does putting in a & after a command work in a bash script at all? The thought was, if I want to run them in parallel, should I do this?
Code: #!/bin/bash
./scripts/dumpthis &
./scripts/dumpthat &
./scripts/dumpsomemore & Where "dumpthis" is just the first snippet of code above.
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Apr 29, 2011
I have a script which basically does many tasks and most of them can run in parallel. The server it runs on has 4 cores, so I changed parts of it to a makefile, and then run them with "make -j 4" which helps a lot. But looking at "top" while it runs, I see it could be improved. Sometimes tasks wait for other servers, so a higher -j value would help. And sometimes multiple tasks are waiting on the same disk, then I think a lower -j value would be better.
The kernel is fairly good at sharing CPU time among the cores, but resources like memory and disks are not shared very well. As an experiment, I tried compiling the kernel with "make -j" with no number. It didn't go very well.
So I wondered if anybody know of a better tool for things like this. I think it should be possible to write something that could change the -j value while it runs.For example:
- Start as many tasks in the background as there are cores. When tasks finish, start another one until done.
- After a little while, check CPU and memory usage to decide if more tasks could run in parallel. Or maybe less?
- If different tasks iowait a lot, check if they wait on the same disk. If so, renice/ionice/suspend some of them. In these situations I think it's better to have them run one after another.
- Other ideas?
I thought of making a script like that, but I doubt I'm the first one with that problem. Also, there are probably lots of things I haven't thought of.
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Apr 5, 2011
Does Debian 6 "Squeeze" automatically run boot processes in parallel if not how do I
configure it to do so. Here is the quote from my /etc/init.d/rc :
# Specify method used to enable concurrent init.d scripts.
# Valid options are 'none' and 'makefile'. Obsolete options
[code]...
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Aug 9, 2011
Trying to write a script for desktop launchers that are adaptable to screen resolution. Ideally, the program should:
1. Determine screen resolution:
if "a" use xdotool options window size 1305 x 869 px and move to 135,0
if "b" use xdotool options window size 1545 x 1019 px and move to 135,0
2. Check if program running:
if no, open program, and use "a" or "b" placement options, focus window
if yes, focus window
3. Close script and leave program open (if possible).
Problems arise when trying to use the script on programs that run from and hog the terminal
(e.g. brasero, gcalctool, nautilus)
Here the script will load the program, and nothing else (probably because it still occupies the terminal as it runs)
Code:
gcalctool && xdotool search "calculator" windowmove 135 0
This next command will cause the program to load, move, but it keeps focusing itself like xdotool is running the windowmove function constantly - it keeps focusing itself until script stopped.
Code:
gcalctool & xdotool search "calculator" windowmove 135 0
This had the same effect as the above code, but seems to work as a conditional subscript running when the process is running in the terminal - it just goes infinitely.
Code:
while [1] ; do xdotool search "calculator" windowmove 135 0 done exit
Is there some kind of "if, then" or "while, do" or some kind of conditional I can put in to the script ensure the window is moved only once if the program is running within the terminal? Is there a way to remove the program from the terminal from the script once it's been called?
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Nov 12, 2009
I am not sure if that Subject really explains it, basically I have a script that executes a CLI java-applet that requires a passphrase from the user. I can easily execute this by issuing the -p argument followed by the passphrase however that shows up on possible logs or at least on the results of the ' ps ' command. If you do not supply this -p argument it provides a new line with the echo " Enter Passphrase: " and asks for input.
how can I provide a result/input for the Passphrase request and is it still possible to throw this application in the background with the ' & ' following the command? I have seen a few examples that show a /bin/expect that expects a result and sends a command however I would like to refrain from any extra dependencies. Example of Regular Execution of application:
Code:
$ /usr/local/***/**** -u USERNAME -r Default-Realm -f certificate.der
Password:
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Jul 30, 2011
I tried a little C programming, and got a bunch of segmentation fault the first few tries. But from what I understand, the whole purpose of segmentation faults is the protect other programs from the damaging effects of my program. Yet, if I trigger a segfault enough times, weird things happen to my other running programs. I usually run a console inside Kate, and after 10 or so segfaults, Kate sometimes freezes or randomly highlights text, etc. just random behavior. Also, my desktop will occasionally hang and things will start failing, like copying files and such. I have to log out to restore everything to normal, but logging out is difficult since the logout prompt freezes. I have never experienced such behavior before I began programming, my system has been relatively stable. I run my program from inside Kate's console, so I was wondering if all KDE applications share memory or something, because this has happened once or twice, and only when I trigger a segfault many times.
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Jul 18, 2010
~$ sed s/^bb/bbbbbb/ foo1.txt
~$ sed: -e expression #1, char 3: unterminated s command
~$
Where 'b' stands for space. What is the error here? Sed is running under bash.
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Feb 26, 2011
I'm having trouble trying to make a script. What I want to do is check if xScreenSaver is running in my user account. If not, run it. If it's running, kill it.
So this is the script I've made:
Code:
The problem is that I've echoed the output of $(pgrep -u $(whoami) xscreensaver) and it always seems to add 4 numbers to the pid, even if the pid doesn't exist. What do I mean by "doesn't exist"? That no xscreensaver is running in my user, and if I run pgrep -u $(whoami) xscreensaver in bash, I get not output, but if I run the command though the script, I get (for instance) 4050. If I run it again, I get 4054, and again 4058... etc. What the hell is going on with that?
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Feb 5, 2010
We have a custom app that runs on boot on some older hardware running DSL linux, and their startup manager was quite simple. We purchased some newer Asus eeebox's which run xandros and things are quite stable and run nice with 1 exception.The application only runs from the root (/) location. This box auto logs in as 'user' and there is a /home/user/.kde/Autostart folder where you can stick scripts to run at boot. So I have a start.sh script, and with little bash programming tried things such as;
sudo cd /
sudo /startapp.pl
but the errors start spewing with the basic;can't find data/xyz as it's looking in the local.I thought there was a basic cwd (change working directory) but everything I try just forces the run from that location.Any ideas or suggestions are appreciated, but things like can you change the code, etc. can't be done, so it must be a programming thing. The only other thought I had but not sure, can you do a cronjob with @boot or something, that when the box starts, it can run this job as root and fire off?
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Feb 15, 2011
is this a good way of doing it? Shall I use & when starting the new process? Itested in bash and dash.
testbash=$(ps -e | grep $$ | grep bash)
if [ 0 = ${#testbash} ]; then
echo "new process"
[code]...
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Feb 16, 2011
I have a bash script that I want to be running on a "clean" screen, but when the script finishes/exits I want to see what was previously on the screen. Any thoughts? The "Clear" command does not enable me to get the information back, and the "Screen" Command runs the program in the original window, so you see nothing until the new screen is exited.
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Aug 18, 2010
how can i run a bash script script by using java in rhel5... then please reply....i have vary good project in my mind.....
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Mar 21, 2010
I have around 600 empty text files that I need to add the name of this file as part of the data, I meanfiles from "file1.txt to "file599.txt, all of them empty, and I need to get the name inside the file, so, when I open the file show the name as part the data "file1".these files were created on my web site, I am thinking in a small script in bash
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Mar 17, 2010
I am writing a script based image manipulator but i need to know if X is running so i can tell if i use CACAVIEW to imagemagick DISPLAY command.
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Jun 14, 2010
I am running a simple script that I copied from slug.ceca.utc.edu/docs/2009-3-26-linux-server-health.pdf and edited with the names and paths of my own servers. I don't know much about scripting (re: nothing) but I wanted to try and be efficient in my new role as a Linux Sys Admin. The script was saved to root's home directory and runs as part of root's crontab once a week. The script runs with no problem, but it doesn't actually seem to run all of the commands contained within. It skips some in the middle and the end and I don't know why. The script itself is this:
Code:
#!/in/bash
uname -a > /tmp/server.txt
[code]...
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Oct 30, 2010
How do you catch user input while the script is running? Or, how would you make two scripts run at the same time, but use input from one script to the other? The program I'm trying to make, echos text on the screen continuously, but while thats happening, I want the user to be able to input something, so the program can detect the input and display something else. So I thought maybe I could make two scripts run to do each task.
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Apr 5, 2010
I am a newbie user in Linux. I have installed a package were it has EMC2 software but when I run it shows parallel lines on the screen while running? What is the cause for it ? Should I reinstall ubuntu again? I had taken a screen shot and it will tell you what I really mean? This is the screenshot, [URL].
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Nov 27, 2010
I use an application called redbutton-browser to access some of the things available on the redbutton digital tv channels. It compiles fine if I use a simple make but fails if I try to run parallel jobs with make -j4. I'd like some help altering the Makefile so that it does a few commands sequentially before it does the rest of the Makefile in parallel.
The relevant bit of the Makefile looks like this:
Code:
ISO13522-MHEG-5.c:xsd2c.c ISO13522-MHEG-5.xsd add_instance_vars.conf add_rtti.conf
make xsd2c
./xsd2c ISO13522-MHEG-5.xsd
./add_instance_vars ISO13522-MHEG-5.c ISO13522-MHEG-5.h
./add_rtti ISO13522-MHEG-5.c > rtti.h
[Code]....
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Aug 13, 2010
Is there a way to use exec, but if exec fails to go on with the script?
Example:
Code:
#!/usr/bin/env bash
exec startx
echo "Starting of X failed"
If startx fails, the echo will be seen on the screen. I tried all kind of stuff, but guess it ain't of much use to post it here. I searched the web, but searching for "exec and bash" in one sentence does give results which are not what i am looking for.
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Feb 25, 2011
I am doing a project where 2 clients connect to server and communicate (chat) and transfer data one after other using sockets. I have working code for this in C language. Now our main aim is to create a communication link where two clients transfer multiple streams data parallely. To be more precise i want to transfer images files and audio files parallel at same time, so is it possible to send data parallel using one socket connection?
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May 29, 2011
i want to know whether we can write a shell script which can utilize 2 CPU's of a cluster...I heard its possible through C Shell [URL] But im familiar with bourne shell only....So is there a possibility to write Parallel Scripts.
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Mar 18, 2010
I need to spawn 2 processes in parallel and each takes an hour or so to finish. Is the following one of the correct ways of using `at` in a script run by crontab?
Code:
#!/bin/bash
# define the env var, cd, etc... assume everything ok up to this point
date +"The start time is %H:%M:%S"
rm -f a.fin
at now <<END_OF_AT
do_a &> a.log
[Code]....
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Jul 29, 2011
I came across some problems. I need to conduct parallel computing on CUDA. I input "uname -a"and read these: "Linux BXSJC 2.6.38.8-35.fc15.i686 #1 SMP Wed Jul 6 14:46:26 UTC 2011 i686 i686 i386 GNU/Linux". I use CUDAtoolkit 4.0. when I input: cd /home/bxsjc NVIDIA_GPU_Computing_SDK/C and "make -i ",the computer returns
[Code]...
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Aug 8, 2010
I have a little hardware project and I would like to use the parallel port. I basically want to display status code on top of other custom peripheral on an headless server. I only use output as the display (7 segment) is not part of the device itself. The problem is, the parallel port only have 8 standard I/O pins. I have read somewhere that there is a way to change the mode of the port to enable more data pins using a specification not backward compatible with the "classic" mode (so not enabled by default). I didn't find any other information about this. As I would like to have all 17 non-ground pin to avoid using more circuitry than necessary, how to turn this mode on?
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Jun 8, 2010
how to set the subject of this up.. but here is what I am trying to accomplish (please keep in mine, this is only my first month playing with ANY Linux programming): My shared web host limits running 2 CRONS or 2 SSH sessions at one time. I need to run more than that.. So, my solution is to run what I need on my home computer, and then push all the results via SSH to my web server.
To keep things timed, I am trying to call 4 bash scripts from inside of 1 bash script... Each bash script has variables I need to export out to the remote (web) server. Being that I can only run 2 SSH or 2 CRON sessions on the remote, it wouldn't do me any good to open up CRON or SSH remotely or locally - either way I'm maxing out. That is why I would like to call 1 final script that takes the output of the 4 bash scripts and does the job.
Main bash calls via CRON every 30 minutes:
Code: ./script_1 &
./script_2 &
./script_3 &
./script_4 &
[code]....
I need to scp the file saved by wget to the remote server. I also need to pass the SQL statement generated in each script as a command in SSH. I'm lost how to get the info from "script_x" into a string that can be used to SSH - and doing this all inside of ONE SSH command. Would I store the SQL strings in a file and call that in the SSH command line?
If so, what is the command to make sure the variable output in the "script_#" file is sent to a file? Can I call the variable from the main Bash Script? Now - the good news is, I can SSH from my local machine to the remote one.That is about as far as I got.Again - I am so new to this that my ears are still wet. This has been something I have been working on for a while, and I'm just lost at this point.
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Jul 17, 2010
below are the details of my system. I have bash as my current shell, some really common commands aren't working.
Do I need to do a re-installation of bash? Or how do I install a selection of bash commands which I need? (for example a subset of [URL])
Code:
root@sdptfw:~ # uname -a
Linux sdptfw.sdpt.co.za 2.4.36 #1 Tue Jul 22 13:13:24 GMT 2008 i686 i686 i386 GNU/Linux
root@sdptfw:~ # echo $SHELL$
/bin/bash$
[Code]....
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Sep 3, 2010
I'm looking for a way in Perl to be able to take a list of servers, ssh multiple commands to it and store the results. If I do this process serially, sometimes one server will hang the whole script and if it doesn't, it still takes hours to complete.
I'm thinking what I need to do is make a parent loop that calls out a separate process that passes the server name to the child sub process and then executes all the commands I have defined in its own process. If one server 'hangs', at least that won't stop the script from doing all the other servers in the list.
I'm guessing using the fork() command would serve me best, however, all the online descriptions I have found have been vague at best.
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Oct 15, 2010
Never done it before, don't know how but its due next week. I am a computer systems student and have been required to built a hardware that will be operated by a program in G++ through the parallel ports. The hardware, thats a piece of cake, the software, now that's were the real problem is. I don't even know were to start.
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Aug 25, 2015
You are probably using systemd (check it with ps --pid 1) and therefore /etc/init.d isn't considered for autostart. Here can you find some information about systemd and autostart [1]. As far as I know systemd isn't intended to start applications with systemd. I recommend you to use the autostart feature of your window manager or desktop environment or at least the .xinitrc.
[URL] ....
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