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Is there a limit to how many jobs you can have running in the background when using command prompt? I've heard varying answers to this question, but is there a concrete number that is set as the limit?

Jeff Schaller
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nosferatwo
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2 Answers2

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This is defined in each shell's source code for jobs as the size of the job table and presumably it should keep a general resemblance with the resource limit for maximum number of processes of a user.

In bash it's 8192, from jobs.c of bash source code:

#if !MAX_CHILD_MAX
#  define MAX_CHILD_MAX 8192
#endif
heemayl
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As foreground/background is entirely a shell thing (it might affect which filehandles are passed to a process, but that can be affected in other ways), such a limit would have to come from your shell. I've never heard of a shell setting a limit, and as far as I can tell, it would require more code for no real gain, so I doubt any shell does, but there are lots of shells I haven't tried and (probably) more I haven't even heard of.

Henrik supports the community
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  • I'm fairly new to Linux and use the bash shell pretty much 99% of the time. I know foreground processes are limited to one at a time since the process consumes the command line, but as far as you know, bash has no limit on background processes? – nosferatwo Mar 28 '16 at 01:31
  • Bash uses a [linked list of a structure](http://git.savannah.gnu.org/cgit/bash.git/tree/jobs.h) so memory might be a limiting factor, if cpu isn't – Jeff Schaller Mar 28 '16 at 01:37
  • Each process consumes a number of file descriptors, which are also finite resources. –  Mar 28 '16 at 01:42
  • @JeffSchaller: I hadn't thought of that. that might actually set a limit, but I'm guessing it will be pretty high. – Henrik supports the community Mar 28 '16 at 01:46