Mubashir Ali :
This is confusing me.
false || echo "Oops, fail" # Oops, fail
true || echo "Will not be printed" #
true && echo "Things went well" # Things went well
false && echo "Will not be printed" #
true return 0 exit code and false returns 1. I am unable to understand how || and && are working. Do both of them work on exit codes or the actual output of the command? What is the difference between && and || operator here?
The above code snippet is from the missing semester of your CS education lecture 2.
chepner :
x && y executes x, then only executes y if x succeeds (i.e., has an exit status of 0)
x || y executes x, then only executes y if x fails (i.e., has a non-zero exit status)
The output of x is irrelevant.
One place they do not differ is in precedence. Unlike Boolean operators in other languages, && and || have equal precedence, so something like
a || b && c
is parsed and evaluated the same as
{ a || b; } && c
rather than
a || { b && c; }