8

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.

  • 3
    Probably yum provides whatis and yum provides apropos will both list the same man, man-db or similar package. Actually whatis is the same as man -f and apropos the same as man -k. See whether those two switch's description in man man is easier to understand. – manatwork Mar 24 '13 at 16:47
7

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.

3

whatis ls lists the manual pages for ls, apropos ls lists all manual pages that contain ls in their title. The first list here gives 2 entries, the second 1385.

0

they act the same with one different: whatis need a accurate parameter:

whatis passwd

But apropos need a string or first characters of something that you know:

apropos pass

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