readlink

Replicate readlink -f as bash script using mainly dependencies available on most platforms:

• readlink (without options)
• cd
• pwd -P
• dirname
• basename
• test -e (as [ -e <file> ])

Known issues

• When readlink is part of a pipe some links contain the current pipe described like pipe:[123456] where the number changes on every call.
  readlink resolves these as valid links.

  e.g.

  $ readlink -f /dev/stdout
  /dev/pts/0
  
  $ readlink -f /dev/stdout | cat
  /proc/737861/fd/pipe:[2332393]
  
  $ ./rdlink.sh /dev/stdout
  
  

  Whereas rdlink is not able to evaluate such links, because the pipe is already invalid as soon as a expression like result="$(readlink "${tocheck}")" returns.