I've been modifying my interfaces file and in numerous places I see the use of the keyword $IFACE in various contexts. I can find no mention of it in the manpages. What does this mean? Is it a keyword understood by the interfaces file or am I supposed to change it to something to tailor examples for my system?
1 Answer
IFACE is an internal variable for ifupdown (ifup and ifdown), could be used in the relevant configuration file /etc/network/interfaces (and on files from relevant directories).
The variable IFACEexpands to the name of the interface being processed currently by ifup or ifdown.
Like all configuration files' man pages, the manual for /etc/network/interfaces is in section 5, and you can easily get that with man 5 interfaces (or even with man interfaces if nothing like interfaces exists in any prior sections).
To get to the variable IFACE in one go, leverage the LESS environment variable (assuming your pager for man is less, which is the default):
LESS='+/^[[:blank:]]+IFACE' man 5 interfaces
