On: Bash [ -z hello ]

[manicdee]

test is [

[kl4m → manicdee]

Indeed, "test" is exactly like "[" except that it doesn't check that its last argument is a "]".

[vacri → kl4m]

For some reason I've always been amused by "which [". The idea of 'punctuation' being a command or a filename is something that threw me.