I have very dumb problem but can't wrap my head around it
if [[ false || false ]] ; then
echo 'true'
else
echo 'false'
fi
As per http://tldp.org/LDP/abs/html/comparison-ops.html
-o logical or
exp1 -o exp2 returns true if either exp1 or exp2 is true.
These are similar to the Bash comparison operators && and ||, used within double brackets. [[ condition1 && condition2 ]]
so if both are false then it should return false? then why it prints 'true'?
You should run those not as part of the conditional command '[[ ]]':
if false || false; then
echo 'true'
else
echo 'false'
fi
As for testing falses within [[ and ]]:
if [[ ! 1 || ! 1 ]]; then
echo 'true'
else
echo 'false'
fi
Noting that [[ false ]] is equivalent to [[ -n false ]] which makes a true condition.
If you like you could make a more apparent and valid conditional test with (( )) like this:
if (( 0 || 0 )); then
echo 'true'
else
echo 'false'
fi
"" (the empty string) is probably a more canonical false value in bash; note that ! 0 is just as false in this context as ! 1."false" is not false. "false" is a non-empty string. Non-empty strings are true by default in [[.
[[.