whereis command is used to find the location of source/binary file of a command and manuals sections for a specified file in Linux system. If we compare whereis command with find command they will appear similar to each other as both can be used for the same purposes but whereis command produces the result more accurately by consuming less time comparatively.
Since whereis command uses chdir(change directory 2V) to give you the result in fastest possible way, the pathnames given with the -M, -S, or -B must be full and well defined i.e. they must begin with a /‘ and should be a valid path that exist in the system’s directories, else it exits without any valid result. whereis` command has a hard-coded(code which is not dynamic and changes with specification) path, so you may not always find what you’re looking for.
whereis [options] [filename]
-b : This option is used when we only want to search for binaries. -m : This option is used when we only want to search for manual sections. -s : This option is used when we only want to search for source files. -u: This option search for unusual entries. A source file or a binary file is said to be unusual if it does not have any existence in system as per [-bmsu] described along with “–u”. Thus `whereis -m -u *‘ asks for those files in the current directory which have unsual entries.
-B : This option is used to change or otherwise limit the places where whereis searches for binaries. -M : This option is used to change or otherwise limit the places where whereis searches for manual sections. -S : This option is used to change or otherwise limit the places where whereis searches for source files.
-f : This option simply terminate the last directory list and signals the start of file names. This must be used when any of the -B, -M, or -S options are used. -V: Displays version information and exit. -h: Displays the help and exit.