How do i use command line conditionals on the bash shell prompt?

[vaquitasos]

|| means OR in boolean

&& mean AND in boolean

These are used on the command line to decide if a condition is met.

if the left side of the || is not true, then run the right side of the ||

For example:

$ test -d /var/log/samba || echo "Samba log directory does not exist"
Samba log directory does not exist

The && on the bash shell does the opposite if the left side of the && is true, then run the right side of the &&

For example:

$ test -d /var/log && echo "Log directory does exists"
Log directory does exists