To clarify, process substitution is a Bash shell syntax that replaces the <( ... ) with a filename, but that filename is a named pipe (aka a FIFO) that a sub-shell has opened for writing by the commands inside the parentheses. The command that you pass this to (in Paul's example, ansible-playbook) must open the given "file" and read it from start to end without trying to seek back and forth.
I tried this with the 'ansible' command a while ago and it failed the same way. I assumed that the code wanted to do seeks around the file rather than just read it all, and that was the reason for the failure. I didn't investigate any deeper. I thought it could be a nice way to accommodate dynamic inventory sources, but there might be a good reason you wouldn't want to support it. -Greg On Fri, Sep 12, 2014 at 3:12 PM, Paul Smith <[email protected]> wrote: > Does Ansible not support bash's process substitution > <http://tldp.org/LDP/abs/html/process-sub.html>? > > My project maintains separate inventory files, and there are some > playbooks that need hosts from certain combinations of them. Instead of > having pre-concatenated files that could go out of sync, I'd like to do > something like: > > $ ansible-playbook -i <(cat inventorya inventoryb) playbook.yml > > I get this error though when I try it: > > ERROR: provided hosts list is empty > > I haven't looked at the Ansible source, but this may be because process > substitution uses an fifo under the hood, and Ansible may be strictly > looking for a file, but this is just wild speculation. > > (Ansible 1.7.1) > > -Paul > > -- > You received this message because you are subscribed to the Google Groups > "Ansible Project" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/ansible-project/8c342e6e-0605-4f8a-be47-bbd8491504bf%40googlegroups.com > <https://groups.google.com/d/msgid/ansible-project/8c342e6e-0605-4f8a-be47-bbd8491504bf%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Ansible Project" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/CAPdwyX6YUF8fjYG42Y7pZSuYZ5hySGbyGJ-8_HYjfe3DV%2Bt%3Dxg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
