s6
Software
skarnet.org

The s6-fdholder-retrievec program

s6-fdholder-retrievec talks to a fd-holding daemon on its open descriptors 6 and 7, and retrieves a file descriptor from it, then executes a program.

Interface

     s6-fdholder-retrievec [ -D ] [ -t timeout ] id prog...

• s6-fdholder-retrievec expects to talk to a listening s6-fdholderd program on its descriptors 6 and 7.
• It attempts to retrieve a copy of the file descriptor that has been stored into that daemon under identifier id.
• It then executes into prog..., with the retrieved file descriptor as standard input.

Options

• -D : delete the file descriptor from the server's storage after retrieval. This option requires writing rights over the given identifier as well as reading rights: check the server's configuration.
• -t timeout : if the operation cannot be processed in timeout milliseconds, then fail with an error message. Communications with the server should be near-instant, so this option is only here to protect users against programming errors.

Notes

• s6-fdholder-retrievec is the "internal" version of s6-fdholder-retrieve. It simply expects to be run as a UCSPI client, i.e. talking to the server over descriptors 6 and 7, instead of connecting to the server itself.
• The error messages for the s6-fdholder suite are explained here.