Centos – the difference between the whatis and apropos commands

centoscommand linerhel

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.

Best Answer

whatis displays one-line manual page descriptions, intended to give you a general idea of what a program do,

while apropos searches the manual page names and descriptions, intended to help you to learn what program to use when performing a certain job.

Some examples

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

UPDATE:

Since both whatis and apropos search man database, you can only get info on what's already installed on your system.

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