When you need to often check things in two different paths which are quite long, it’s really a pain to keep typing them again over and over. Luckily, you don’t have to.
There is an environment variable which contains the path you were at before changing directories:
# cd /var/log # cd /usr/lib/gcc/ # echo $OLDPWD /var/log
So basically all you need to type to get back to /var/log is:
Well it isn’t really short either so you’d probably want to create an alias or something… We’re again lucky since the cd command actually already has a solution for us:
# man builtins ... cd [-L|-P] [dir] ... An argument of - is equivalent to $OLDPWD. ... if - is the first argument, and the directory change is successful, the absolute pathname of the new working directory is written to the standard output. ... ...
is equivalent to:
cd "$OLDPWD" && pwd
which changes to the previous working directory and then writes its name.
An alternative to this is to use pushd and popd:
#cd /var/log # pushd /usr/local/bin /usr/local/bin /var/log # pwd /usr/local/bin # popd /var/log
The difference is that pushd builds a directory stack, so you can use it to push more than 1 directory and use popd to travel back in the stack. But it doesn’t allow you to go back and forth over and over.