CentOS 6.3 / RHEL 6.3
Can someone please explain the difference between the
whatis command and the
apropos command? I noticed that both appear to be installed by default and I'm not sure what the difference is between them.
whatis displays one-line manual page descriptions, intended to give you a general idea of what a program do,
apropos searches the manual page names and descriptions, intended to help you to learn what program to use when performing a certain job.
Say, I want to know what does
df program do.
whatis gives me answer.
$ whatis df df (1) - report file system disk space usage
And now, I want to unzip an archive.
apropos gives me some choises for consideration.
$ apropos unzip bunzip2 (1) - a block-sorting file compressor, v1.0.6 funzip (1) - filter for extracting from a ZIP archive in a pipe gunzip (1) - compress or expand files lz (1) - gunzips and shows a listing of a gzip'd tar'd archive preunzip (1) - prefix delta compressor for Aspell unzip (1) - list, test and extract compressed files in a ZIP archive unzipsfx (1) - self-extracting stub for prepending to ZIP archives uz (1) - gunzips and extracts a gzip'd tar'd archive
apropos search man database, you can only get info on what's already installed on your system.