I think this is a problem with the precedence of && vs ||. If INSMOD is not set, it will work as you intend, but once it's set, only the || branch will execute. You can fix it if you group the assignments together: [ -z "$INSMOD" ] && (INSMOD=$(which modprobe) || INSMOD="$(which insmod)") On Sat, Feb 27, 2021 at 01:32:55PM -0800, Kenneth Porter wrote: > In the sqm-scripts package for managing network traffic shaping is this line > for finding a program suitable for loading the kernel shaping modules: > > [ -z "$INSMOD" ] && INSMOD=$(which modprobe) || INSMOD=$(which insmod) > > It seems to set INSMOD to /usr/sbin/insmod, even though /usr/sbin/modprobe > is available. (Both are symlinks to ../bin/kmod.) > > According to this article, the return value of the first assignment should > be success and it shouldn't take the fallback statement: > > <https://unix.stackexchange.com/questions/270828/how-is-the-return-status-of-a-variable-assignment-determined> > > Also working the issue here: > > <https://github.com/tohojo/sqm-scripts/issues/133> > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos -- -- Skylar Thompson (skylar2 at u.washington.edu) -- Genome Sciences Department, System Administrator -- Foege Building S046, (206)-685-7354 -- University of Washington School of Medicine