NOTE.md

NOTE

Supplementary information

cd command compatibility

[exit status]	ash	bash	bosh	dash	ksh	mksh	posh	yash	zsh
cd ""	0	0	1	0	1	0	0	0	0
cd -P ""	0	1	1	0	1	1	1	1	0
cd -L ""	0	0	1	0	1	0	0	0	0

readlink command compatibility

GNU coreutils

$ cd /tmp
$ ln -s no-such-a-file symlink

$ readlink symlink
no-such-a-file # exit status: 0

$ readlink -f symlink
/tmp/no-such-a-file # exit status: 0

$ cd /
$ readlink -f /tmp/symlink
/tmp/no-such-a-file # exit status: 0

busybox 1.31.1

$ cd /tmp
$ ln -s no-such-a-file symlink

# OK
$ readlink symlink
no-such-a-file # exit status: 0

# BAD
$ readlink -f symlink
<none> # exit status: 1

# BAD
$ cd /
$ readlink -f /tmp/symlink
/tmp/symlink # exit status: 0

macOS

$ cd /tmp
$ ln -s no-such-a-file symlink

# OK
$ readlink symlink
no-such-a-file # exit status: 0

# -f not implemented
$ readlink -f symlink
readlink: illegal option -- f # exit status: 1