The whence Command

The whence command can be used to determine exactly where the command you specify is located. For instance, it may be a command located on the disk drive, it may be an alias, or it may be built-in to the Korn shell. whence reports the proper location.

whence

$  whence ls    <works with basic commands>
/bin/ls

$  whence dir   <works with aliases>
/bin/ls -al | more

$  whence echo  <works with built-in commands>
echo