I need to control daemons like dhcp/bind from within a perl script. I could run the script as root to restart/stop/start the daemons however, this is not good for security.
What are the ways of controlling processes within perl as different users?
My computer for a project I'm working on will be using Ubuntu with Perl and VLC from the repositories, if that matters at all. I'm not sure what I should/could use to accomplish this, but essentially I'm looking for Perl to be able to send predefined data via a serial connection based on the time within a song that VLC is playing.
A couple of the things that I've thought about after Googling a bit are SMPTE and subtitles/lyrics; I can't stop thinking that there's got so be a simple way that I'm just overlooking, though - most of the stuff I've found is for over-the-network applications, and that's overkill for this situation. All the subtitles/lyrics would have for text is hexadecimal values; all the SMPTE would do is keep Perl and VLC (playing audio) in-sync with each other. I would need either one or the other, but not both. Or, I could use something else...
I'm envisioning something like the setup below, I just don't know what else I need to make it happen.
Files:
song.mp3
timing.txt
script.pl
When I run "./script.pl song.mp3 timing.txt", VLC will open, and start playing "song.mp3", and the variable "$mils", for milliseconds elapsed, will be equal to zero. For each line in "timing.txt", the "script.pl" will assume the portion before an underscore is the "$time" for that line (time in milliseconds), and "script.pl" will assume that the portion after the underscore is the "$data", a three-byte hexadecimal value (such as "ff101f", or "011c00"), for that line.
I think that I will need to use two arrays, "@time" and "@data", such that the given line in "timing.txt" would read the same as printing: "$time[$line]".'_'."$data[$line]"."
" (if "$line" is the line number). My problem: jitter/stuttering playback. If VLC stumbles (which it sometimes does), and is a about half a second behind where it "should" be, but Perl didn't stumble, then I've got an out-of-sync issue.
Since Perl can't just count the time by itself to avoid synchronization issues, I've got two main ideas for getting this done: One way: Perl has to "read" where VLC is at, and use that as the "$mils" value. Then, if VLC delays/stubmles, so will Perl, but everything will still be in-sync. Alternative way: VLC has to "listen" to what Perl says "$mils" is at any given moment, essentially having Perl be in control of VLC's timing. This would make VLC "skip ahead" (to where it "should" be) if it starts to fall behind, thus keeping the two in sync.
I don't know which, if either, of these ways is best for my particular need. I would need "script.pl" to send "$data[$line]" over the serial connection when "$mils" == "$time[$line]". I already know how to send serial data from Perl, read files via Perl, and convert the hexadecimal number (if needed). I don't know how to "link" Perl and VLC so that they stay synchronized, and I am quite lost as to where to go from here.
I'm reading "OReilly Learning Perl 5th Edition", and there are such words:Code:You can use an array element like $fred[2] in every place? where you could use any other scalavariable like $fred.At the bottom of the page, it explains the ? like this:Code:The most notable exception is that the control variable of a foreach loop, which you?ll see later in this chapter, must be a simple scalar.Since Perl has the save-and-restore mechanism for the control variable, why an array element can't be used as the control variable
View 1 Replies View Relatedpretty simple. how would you background a process from a script and get its process id at the same time?
View 6 Replies View RelatedI have a friend (really), who is the author of a Perl application that uses backticks to launch an external application. The process reads a largish set of data files, and printing largish amounts of data which is consumed by Perl. Very rarely, the external application crashes. When it does, the Perl script has been seen to hang, and the host CPU usage goes to 100%. The Perl script can be killed and the host recovers.
The question is whether this is predictable/expected behavior, and if it is, is there anything within Perl which can be used to defend against this behavior. I have already recommended the use of the open() form of reading from a child process, but I'm not sure whether that really accomplishes anything. My theory on the matter is that Perl ends up busy-waiting on the child's output, never receiving any EOF, and consuming all CPU. I cannot see how using open() changes that behavior. I am now interested in this problem so I can avoid causing similar behaviors in the future, and just because 'inquiring minds wish to know'.
EDIT: I suppose I should have added that this is on generic 32-bit Linux hosts; Perl 5.8.X
Is it possible to have an Expect script spawn an SSH session, log in, then go into interactive mode and give control of the SSH session to a Bash script? Here's a simplified example of the script so far:
Code:
#!/bin/bash
expect -c "
[code]....
I've been asked to do certain jobs doing scripts in bash and perl. So this time they asked me to check which users hasn't been able to loggin. DONE with Code: lasb Now they asked me to show how many times all the users have input certain Bash Commands like
Code: Ls Cd pwd I was wondering if there was a command of something that could show me how many times those commands has been used, I already know I can see all input with Code: history Sorry I'm really new to this, been working with this for a couple of weeks, and its really interesting.
What would be the best way to kill or start a process from a web site? Additionally, how could I get the output from the process and display it on the site?
View 7 Replies View RelatedTest 9 brings up this error:
Code:
Test 9: ERROR
--------
Akonadi control process not registered at D-Bus. Details: The Akonadi control process is not registered at D-Bus which typically means it was not started or encountered a fatal error during startup. How can I solve this?
F10 x86_64
akonadi-1.0.0-4.fc10.x86_64
mysql-5.0.67-2.fc10.x86_64
I want to control which users are listed in the GDM login window.
View 2 Replies View RelatedI want to setup a git repository, three of four users will contribute, so they need to download the code and shall be able to upload their changes to the server or update their branch with the latest modifications.So, i setup a linux machine, install git, setup the repository, then add the users in order to enable the acces throught ssh.Now my question is, What's next?, the git documentation is a little bit confusing,i.e. when i try from a dummy user account to clone the repository i got:
xxx@xxx-desktop:~/Documentos/git/test$ git clone -v ssh://xxx@192.168.1.104/pub.git
Initialized empty Git repository in /home/xxx/Documentos/git/test/pub/.git/
xxx@192.168.1.104's password:
[code]....
I'm using Sun One LDAP server, (Soon to be moving to openldap). I have one Master server, no slaves, about 60 user accounts.
I'd like to add an attribute to each of the users DN's to restrict there ability to login to specific hostnames. I.e. I have hosts A, B and C. Dev staff can access A and B, but not C, and support staff need to access all of them.
I found a link at [url] which talked about using 'hostsallowedlogin' and 'hostsdeniedlogin' attributes but I'm presuming these are bespoke. If they are, how do you configure the ldap.conf to take note of these attributes when authorizing access?
I am using Debian Lenny on a cluster. If I log in as a regular user and try to adjust the volume on the top right panel (Using Gnome), I get the following message"The volume control did not find any elements and/or devices to control. This means either that you don't have the right GStreamer plugins installed, or that you don't have a sound card configured.You can remove the volume control from the panel by right-clicking the speaker icon on the panel and selecting "Remove From Panel" from the menu."or ifenter "gstreamer-properties" in the terminal and do a test I get the following message"Autodetect: Could not open resource for writing."
if I become the root user and enter "gstreamer-properties" in the terminal and do a test, the test works. Alsamixer works as root, but not as a user.My user error for alsamixer i"alsamixer: function snd_ctl_open failed for default: No such file or directory"I am not sure what setting I need to change to which all users can adjust the volume. Problem 2:When I put in a usb stick I get the following error as a user.Cannot mount volume
I have a shell script to identify whether the process is running or not. If the process is not running, then I execute another script file to run my application. Below is my script and saved this script as monitorprocess.sh Code: #!/bin/bash
result=$(ps -ef | grep -v grep | grep "applicationname.sh" | awk '{print $2}')
echo $result
if [ "$result" == "" ];
[code]...
Is there any difference in cpu usage for process in init.rc(runs automatic when boot is happened) and manually running process. Will these both have same priority by default...?
View 1 Replies View RelatedI tried googling but didn't get any answer for this.I have a process called "abc" and it is running with PID "123".I have a putty session opened with PID "999".I am giving kill -TERM 123 from putty session.My process "abc" before dying it should catch the PID of the terminal which provided TERM signal to it.Is there any way to find this out
View 2 Replies View RelatedI have my own dedicated server box running (using it for game servers). I access it via ssh and I have root control of it. It has FEDORA Operating System. I wanna give FTP control of different directories to different users. Right now there are no other FTP users except root. I have installed vsftpd and dont know what should I do next? How do I add users (who can read/write/delete files) and How do I restrict them to their home directory?
Here is what I want:
username:client1
password:12345
home directory: home/server1
username:client2
password:12345
home directory: home/server2
For the past few days I was putting effort on understanding the software control flow starting from "Boot loader" to "Linux User space".
I am consolidating the entire process and putting forth in this forum...It would be great if someone can validate this..It might be useful to other new bees too.
Step 1 : Power up the board
Step 2 : The CPU control goes to EEPROM/storage memory where BIOS resides
Step 3: BIOS gets loaded in RAM and gets executed
Step 4: During execution, the selection of Boot device has to be done with the help of BIOS Menu [Blue screen appearance during start up in normal PC's]
Step 5: BIOS shall access the Bootloader stored in boot device [for eg.,Hard disk]. Boot loader is stored in MBR area.
for explanation purpose I take the following configurations
Bootloader = GRUB
Boot Device = Hard Disk
Step 6: GRUB shall be loaded in RAM and gets executed
Step 7: GRUB shall load the KERNEL image to RAM. Kernel image is stored in Hard Disk.
The question of "How the GRUB knows where the Kernel image is stored".
The answer is
1. In the "Grub.config" file, the location of "Kernel Image" and " Ramdisk Image" [which will be discussed later in the section] is being given.
Step 8: Kernel Image followed by Ramdisk Image is loaded in RAM by GRUB bootloader
Step 9: Kernel Image gets executed...During execution, top portion of the code shall make initial hardware initialization and latter part
of the code shall just decompress the Kernel Image
Step 10 : After decompressing the Kernel Image, it shall decompress
the already loaded Ramdisk Image
Ram disk is just creating a temporary hard disk in RAM. The main responsibility includes it consists of minimal driver files, executables, directory structures to created a TEMPORARY ROOT FILE SYSTEM.
This Temporary Root File system shall be used by Kernel Image
1. Execute the executables to access the Hard disk
2. For creating Permanent Root File System in HARD DISK
Step 11 : Kernel Shall look for the file /Linuxrc in Ramdisk. Linuxrc
is a USER script file [not sure]
Step 12: At the end of script file Linuxrc, the Ramdisk shall give the
control to "USER SPACE" [path for writing the script not known]in Linux kernel
Step 13: USER SPACE is the normal shell
I have several local users on a F11 box. I want to keep one of those users from getting to the network. I could upgrade this machine to F12, if it offers a better solution.
View 1 Replies View RelatedAlthough I'm a linux user, I don't know much about the whole booting process myself. I normally have a friend that I can consult when things don't go the way I expected. But here's the thing: he updated my computer and went away. And of course I can't reach him and I really need it to work. And moreover, I want to be able to sole things myself.
The booting process stops halfway. The last thing it says is: can't access tty: job control turned off (initramfs) ...
Where is the perl module for programming with sockets?
View 4 Replies View RelatedA Tomcat server is installed under user A. Now I am going to write a script which will start this Tomcat server. And this script can be executed from other users (from there account). And if other user run this script, the process ID should be of user A, so that user A can start or stop this process any time. This means, at the beginning of the script I have set the process ID as user A. How to do this?
View 8 Replies View RelatedI have a shell script to identify whether the process is running or not. If the process is not running, then I execute another script file to run my application. Below is my script and saved this script as monitorprocess.sh
Code:
#!/bin/bash
result=$(ps -ef | grep -v grep | grep "applicationname.sh" | awk '{print $2}')
[code]...
I want to kill parent process after "fork()" method. but if I kill parent process with "exit(0)" method, main() thread is terminated as well so child prosess doesn't work anymore. Is there any way to kill only parent process without affecting to child process?
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
[code]....
Consider the following code:
Code:
int main()
{
int i=0;
pid_t pid;
for(i=0;i<2;i++)
[code]....
I get the following output:
Parent: chid_pid=4356 i=0 parent's pid=4355
This is child 4356 i=0
This is child 4357 i=1
[code]....
I can observe instead of two children(as I expect) processes there are three. This is because child process 4356 creates its own child. Why all the messages of the type "This is child X i=Y" are concentrated one under another? How exactly fork works? Is affected by the fact that I have a dual-core processor?
I just downloaded Tk-804.028 and try to install it (according to the README.linux) but I get:
> perl Makefile.PL
/opt/ActivePerl-5.10/bin/perl-static is installed in /opt/ActivePerl-5.10/lib okay
PPM for perl5.010001
Test Compiling config/perlrx.c
Test Compiling config/pmop.c
Test Compiling config/pregcomp2.c
[code]...
Any recommendations on what Perl tutorial to use?
View 1 Replies View RelatedI am taking an input from the user for free and Used capacity in a disk. I wish to convert Input entered in MBTB to GB and this is how i am doing it.
Code:
<some code>
print "Enter Total disk space";
$tot = <STDIN>;
convert($tot);
[code]...
how do i pass the value of conv[0] after conversion back to $tot or $use such that they contain only value which is in GB?
I really would like Perl Qt4 bindings. The best I could find is this:[URL]The problem is that the sources would not compile, and the RPMs are for 32-bit machines.Is there really no such thing as good Perl Qt4 bindings?
View 8 Replies View RelatedI am a newbie on linux and just searching everything about perl scripting and modules nearly 3-4 days. I need a perl script but one of not easy to find on searching google. Okay now I need a perl script which create or recreate (edit) id3 tags (artist, comment, album, year, cover) of mp3 files stored on my linux centos server. I installed MP3::Tag version 1.13 pearl module to my server. I Searched tutorials about how to use it, finally I get through reading id3 tag of mp3 file but not achieve to modify it or create a new id3tag.
These are the details:
I have a mp3 file called 1.mp3 this script will process that '1.mp3' file read its id3tag if there is one, than modify or create id3tag for it by my fix artist name for example:
'1.mp3' files id3 tag details are like this
Artist: Dj xx
Year:2010
Title:yyyyy
Comment:eerwer
Cover: x.jpg
Now via this perl script which uses MP3::TAG I will change it's
artist as YYY
Title:ttt
Comment:cool
Cover:t.jpg
these are gonna be my fixed values. I mean all '1.mp3' file will have same artist based on script value.
The reason of this script is I will share Dj podcasts on my server and Dj's would have upload their mp3's which has got different id3 tags and cover pics. etc. I want to create more organized podcasts of them by the way I would trigger this perl script via Cronjob.