Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Creating background process for my shell
Top Forums Shell Programming and Scripting Creating background process for my shell Post 302427386 by hansel13 on Saturday 5th of June 2010 01:11:00 AM
Old 06-05-2010
Creating background process for my shell
I actually posted this problem on a different forum, but figured this would be a more appropriate place to post it.

OK so I've created my own shell, but I can't get the background process function to run properly! What I want to do is to run a process in the background, and also print when the job is finished. The printing part is where I've been having some problems.

So if I type sleep 5 &, it works and prints out when finished. However, if I type sleep 5 &, and then type in another command like ls or ps after it, the shell hangs and it prints out that it's finished when it clearly has not finished.


Code:
void handler(int sig)
{
        int pid;
        int status;
        pid = wait(NULL);
        printf("Pid %d exited.\n", pid);
}



int runInBackground(Command* command, int givenPath)
{
        int pid;
        int status;
        char *commandName = command->name;
        if(givenPath == 0)
        {
                commandName = getCommandPath(command->name);
        }

        if(commandName == NULL)
        {
                printf("Command not found.\n");
                return 1;
        }

        pid = fork();

        if(pid < 0) //Checks for error
        {
        }

        if(commandName == NULL)
        {
                printf("Command not found.\n");
                return 1;
        }

        pid = fork();

        if(pid < 0) //Checks for error
        {
                printf("Error in the fork process.\n");
                return 1;
        }
        else if (pid == 0) //Child
        {
                execv(commandName, command->argv);
                return 1;
        }
        else
        {
                signal(SIGCHLD, handler);
        }
}

OUTPUT:
Code:
<project3> sleep 5 &
<project3>
<project3>
<project3> Pid 399 exited.
<project3>
<project3> sleep 5 &
<project3> ls
bob                 project1.c  hey                 proj1               proj1.c
Pid 402 exited.

I pressed enter a few times the first time I ran sleep 5 in the background, then after 5 seconds, it printed out the pid perfectly! But notice what happens when I ran sleep 5 in the background and then ran ls following it right afterwards. System printed out my files/folders but posted the pid and got hung.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

capture the process id when starting a background process

Hello all, How do I start a background process and save the process id to a file on my system. For example %wait 5 & will execute and print the process id. I can't figure out how to get it to a file. I've tried: > filename 0>filename 1>filename. Any assistance is most appreciated. Thanks, Jim... (10 Replies)
Discussion started by: jleavitt
10 Replies

2. Shell Programming and Scripting

How to include RETURN KEY with Background process "&" in Shell Script

Hello All, I am a newbie in Shell script programming, and maybe you can help me with my query. I need to write a shell script (mntServer.ksh) that will start a background process and also to be able to run another script. The mntServer.ksh script contains: #!/bin/ksh... (1 Reply)
Discussion started by: racbern
1 Replies

3. Shell Programming and Scripting

Background Process Shell Scripting

I have a following program: echofunc() { filename=$1 echo "reading $filename" while read line do echo $line; sleep 6; done < $filename } split -5 new.dat ls x* > input.dat while read file do echofun $file & done < input.dat (3 Replies)
Discussion started by: dhieraj
3 Replies

4. Shell Programming and Scripting

facing problem in starting a process in background using shell script.

hey all, i am working on sun solaris machine and i want to start a process in background using shell script (actually i wanna start tomcat server using shell script). please dont tell me that append a & at last because this is not working in the shell script. i have also used nohup and... (8 Replies)
Discussion started by: dtomar
8 Replies

5. UNIX for Dummies Questions & Answers

Script to start background process and then kill process

What I need to learn is how to use a script that launches background processes, and then kills those processes as needed. The script successfully launches the script. But how do I check to see if the job exists before I kill it? I know my problem is mostly failure to understand parameter... (4 Replies)
Discussion started by: holocene
4 Replies

6. Shell Programming and Scripting

Creating a daemon to run in background

I am trying to create a service to always run and monitor a script that has a tendency to hang, we could not find what is causing it to hang so are in the process of completely reprogramming just about everything, however, that will take upto 6 months. So I need to create this to monitor the... (5 Replies)
Discussion started by: ukndoit
5 Replies

7. Shell Programming and Scripting

How to put FTP process as a background process/job in perl?

Hi, I am using net::ftp for transferring files now i am trying in the same Linux server as a result ftp is very fast but if the server is other location (remote) then the file transferred will be time consuming. So i want try putting FTP part as a background process. I am unaware how to do... (5 Replies)
Discussion started by: vanitham
5 Replies

8. Shell Programming and Scripting

Running Shell Script in the cron, background process

Hi, i was looking for an answer for some trouble im having runing a script in the cron, thing is, that when i run it manually it works just fine. But when cron runs it, it just doenst work. I saw a reply on a similar subject, suggesting that the . .profile worked for you, but im kind of... (9 Replies)
Discussion started by: blacksteel1988
9 Replies

9. Shell Programming and Scripting

Need help in creating a shell script to automate svnstats process

Hi, I am trying to create a shell script to automate the following process of getting svn stats:- Step1:- cd to checkout location. Note that the checked code have multiple modules in respective folders Step2:- Execute this command inside each module:- svn log -v --xml >... (0 Replies)
Discussion started by: d8011
0 Replies

10. Shell Programming and Scripting

Make background process interact with fg process

Hi, I have written a menu driven shell script in which as per the choice, I run the another script on background. For eg: 1. get info 2)process info 3)modify info All the operations have different scripts which i schedule in background using &. However I wish to display the error... (0 Replies)
Discussion started by: ashima jain
0 Replies

LEARN ABOUT CENTOS

platform::shell

platform::shell(n)					       Tcl Bundled Packages						platform::shell(n)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4							platform::shell(n)
All times are GMT -4. The time now is 07:05 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy