Visit Our UNIX and Linux User Community


Running two processes in background


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Running two processes in background
# 1  
Old 05-13-2002
Question Running two processes in background

hi there,

here's what i need in my korn-shell:

... begin korn-shell script

... nohup process_A.ksh ; nohup process_B.ksh &

... "other stuff"

... end lorn-shell script

in plain english i want process A and process B to run in the background so that the script can continue doing "other stuff".

but i want process B to follow process A (not run simaltaneously) i.e. B should start only after A is done. is there a simple elegant way to do this ?

thanks
jacob
# 2  
Old 05-13-2002
have you tried:

nohup process_A.ksh & && nohup process_B.ksh &
# 3  
Old 05-13-2002
hi Cameron,

i got the following error message (the && doesn't seem to work)

ksh: syntax error: `&&' unexpected


still, thanks for replying. do you know of any other possibilities i might want to check ?

jacob
# 4  
Old 05-13-2002
just to pre-empt the following solution:

one easy way to solve this would be have "nohup process_B.ksh" as the last line in process_A.ksh.

however, this is for a automation/scheduler piece that i am trying to write and process_A is any system user's process, while process_B is a sort of cleanup process done by the scheduler module. in the interest of keeping things unchanged for the eventual users - i don't want users to have to modify all their "process_A"s to include a line for process_B.

just in case, someone came up with the above solution

thanks
jacob
# 5  
Old 05-13-2002
A bit of quick reading ...

Try: (nohup process_A.ksh; nohup process_B.ksh)&
# 6  
Old 05-13-2002
Quote:
Originally posted by Cameron

Try: (nohup process_A.ksh; nohup process_B.ksh)&
I am a little worried about this. The parentheses create a subshell and the ampersand puts this subshell into the background. The subshell then uses nohup to run the first process and then it uses nohup to run the second process. The problem is that the subshell itself is not nohup'ed.

I think that
nohup sh -c "( A ; B )" &
will avoid this problem.
# 7  
Old 05-13-2002
Quote:
Originally posted by Perderabo


I am a little worried about this. The parentheses create a subshell and the ampersand puts this subshell into the background. The subshell then uses nohup to run the first process and then it uses nohup to run the second process. The problem is that the subshell itself is not nohup'ed.

I think that
nohup sh -c "( A ; B )" &
will avoid this problem.
hi Perderabo,

great solution ! works just like i wanted it to.

Perderabo - you were right about the subshell not being nohup'ed

Cameron - thanks for initiating the solution-thought. greatly appreciated.

thanks folks
jacob

Previous Thread | Next Thread
Test Your Knowledge in Computers #843
Difficulty: Medium
HTTP cannot directly support file transfer.
True or False?

10 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

List all background processes

How do I list the process in a Unix based system which are running in background? The following are options that I'm aware of, but they may not be appropiate. a. using ps -ef , and getting records of processes for which STATUS='S'(uninterruptible sleep) b. using jobs -l, and filtering... (5 Replies)
Discussion started by: kumarjt
5 Replies

2. Shell Programming and Scripting

Need help on background processes

Hi, I have a schell script parent.ksh from which I am calling three background processes a.ksh,b.ksh and c.ksh. Once these three processes completes the next step in parent.ksh should execute. How to achieve this? Please help me.... Thanks... (1 Reply)
Discussion started by: ravinunna
1 Replies

3. UNIX for Dummies Questions & Answers

Query on Running Multiple processes in background

HI All , Pardon me for asking some very basic questions, I would be grateful if someone can help. I am trying to execute a shell script which runs multiple processes in background. It includes various operations like copying , DB operations etc etc. Now problem is that the complete script... (6 Replies)
Discussion started by: gpta_varun
6 Replies

4. Shell Programming and Scripting

Background Processes

Ok guys so I have my first dummy shell almost done except for one tiny part: I do not know how to run a process in the background, from the code! I already know how to do that in a normal shell: $ program & However, no clue when it comes to how to program that thing. :eek: A very... (2 Replies)
Discussion started by: Across
2 Replies

5. Solaris

About running processes in background

Hi, I need to establish a procedure that will start an application in background each time my remote Solaris server is (re)started. This would be a kind of daemon. I am no sysadmin expert, so I am looking for pointers. How should I proceed? What are the main steps? Thanks, JVerstry (9 Replies)
Discussion started by: JVerstry
9 Replies

6. UNIX for Dummies Questions & Answers

Disadvantage of background processes

Hi, Inorder to improve the performance, I am trying to execute my command as a background process.. For eg: To zip large numbers of files present in a directory instead of using a single process, i do follow the below method: gunzip -c > / &... (3 Replies)
Discussion started by: unni.raj
3 Replies

7. Shell Programming and Scripting

Keep a certain number of background processes running

I've got a bit of code I'm trying to work on... What i want to happen is ... at all times have four parallel mysql dump and imports running. I found the follow code snippet on the forum and modified it to work by starting four concurrent processes but it waits until all four are done before... (7 Replies)
Discussion started by: dgob123
7 Replies

8. SuSE

oracle background processes

I have installed oracle 10g on suse sles9. I do not see oracle background processes. ps -ef|grep ora_ gives me environment variables junk. ps -ef|grep smon does not show anything however database is up and running. Any idea how to tweak that? (1 Reply)
Discussion started by: vijayasawant
1 Replies

9. Linux

Question about background processes

Hi! First of all, let me warn you I'm quite new to the world of LINUX and Operating Systems understanding, so that's why I pose these newbie and stupid qustions... Anyway, I'm trying to build my own simple shell in C and I'm getting some problems in implementing the background process ('&')... (10 Replies)
Discussion started by: neimaD
10 Replies

10. UNIX for Advanced & Expert Users

Background processes

How do you capture the return code from a background process? I am dumping data to a fifo and then processing it in a c program. I need to know that the sql finished successfully to ensure no missing data. Thanks. ex. sqlplus user/password < get_data.sql > data_fifo.txt & bin/process_data... (2 Replies)
Discussion started by: korndog
2 Replies

Featured Tech Videos