Answer by tlake29 for What's a "canonical path"?

A good definition of a canonical path is given in the documentation of readlink in GNU Coreutils. It is specified that 'Canonicalize mode' returns an equivalent path that doesn't have any of these things:

1. hard links to self (.) and parent (..) directories
2. repeated separators (/)
3. symbolic links

The string length is irrelevant, as is demonstrated in the following example.

You can experiment with readlink -f (canonicalize mode) or its preferred equivalent command realpath to see the difference between an 'absolute path' and a 'canonical absolute path' for some programs on your system if you are running linux or are using GNU Coreutils.

I can get the path of 'java' on my system using which

$ which java/usr/bin/java

This path, however, is actually a symbolic link to another symbolic link. This symbolic link chain can be displayed using namei.

$ namei $(which java)f: /usr/bin/java d / d usr d bin l java -> /etc/alternatives/java   d /   d etc   d alternatives   l java -> /usr/lib/jvm/java-17-openjdk-amd64/bin/java     d /     d usr     d lib     d jvm     d java-17-openjdk-amd64     d bin     - java

The canonical path can be found using the previously mentioned realpath command.

$ realpath $(which java)/usr/lib/jvm/java-17-openjdk-amd64/bin/java