Having x AND y, then nagating it you get: NOT (x AND y). This is equal to (NOT a) OR (NOT b). It is not equal to (NOT x) AND (NOT y).
I want to check if a file is a file and exists and if it is not empty
If you want to check if a file is a regular file and if it is not empty, then you do:
[[ -f path ]] && [[ -s path ]]
The negation would be (each line is equal) (note De Morgan's law):
! ( [[ -f path ]] && [[ -s path ]] )
[[ ! -f path || ! -s path ]]
Which you can write also as (each line is equal):
! [[ -f path && -s path ]]
[[ ! ( -f path && -s path ) ]]
[[ ! -f path ]] || [[ ! -s path ]]
# or using `[` test and `-a` and `-o`:
! [ -f path -a -s path ]
[ ! -f path -o ! -s path ]
[ ! \( -f path -a -s path \) ]
So just:
if [[ ! -f "/path/to/dir/" || ! -s "/path/to/dir/" ]]; then
echo "The /path/to/dir is not a regular file or size is nonzero"
else
echo "The path /path/to/dir is a regular file and it's size is zero"
fi
I'm side-eyeing the slash on the end of
/path/to/dir/and thinking it's worth comment, but having a hard time articulating this morning. Maybe add a note at the bottom as an aside to clarify that if the slash is there, it is a directory?@Kamil Cuk mybe you are using different Bash version (I am on 4.1.2(1)-release) and -s is not enough. If I pass existing directory path like this:
if [[ -s "/opt/gmdemea/smartmap_V2/maps/" ]]; then echo "Exists"; else echo "Does not exists"; fiit returns 'Exists' while it is not a file so should be going to else clause and return 'Does not exist'.@PiotrPanczyk you are right. I think it's treating dir as a file with zero size... : /
@EdMorton I think because theoretically
[[ a ]] || [[ b ]]will run two processes while[[ a || b ]]will run only one. Note that thebis not processed ifais false in both cases. Less processes usually result in faster scripts. And it's less to type. I admit, I didn't give that statement enough thought (but I think I stand by it anyway and will still use&&||inside[[in my scripts)@KamilCuk I understood '-s' same as you and used in alone in the code and it got me into troubles. That's why started to investigate this.