Applies To
- Linux
- man pages
Issue
When searching the short descriptions and manual page for a keyword, the man utility may return an empty set, for example:
# man -k ndctl
ndctl: nothing appropriate.
Cause
If you built ndctl from source, the man page indexes may not have been automatically generated for you. Additionally, if you installed ndctl to a non-default location, your $MANPATH shell environment variable may not been updated to point to to the new man page locations.
Solution
1) Verify the current system global search paths for manual pages
# manpath -g
/usr/man:/usr/share/man:/usr/local/man:/usr/local/share/man:/usr/X11R6/man:/opt/man
2) Identify if these paths are overridden by a local MANPATH setting, for example the following shows no additional search paths
# echo $MANPATH
#
3) If the install location of ndctl is not included in the above output, add the path to your MANPATH shell environment, otherwise skip this step:
# export MANPATH=$MANPATH:<path_to_ndctl_man_pages>
4) Manually scan and build the man page indexes
# sudo mandb -c
This command may take a few minutes depending on the number of search paths and man pages it has to index. The output is verbose as it scans and indexes. Once complete, it will provide a summary:
...
118 man subdirectories contained newer manual pages.
10550 manual pages were added.
0 stray cats were added.
5) If the ndctl man pages were scanned and indexed, man -k ndctl will now work as expected, eg:
# man -k ndctl
ndctl (1) - Manage "libnvdimm" subsystem devices (Non-volatile Memory)
ndctl-check-labels (1) - determine if the given dimms have a valid namespace index block
ndctl-check-namespace (1) - check namespace metadata consistency
ndctl-clear-errors (1) - clear all errors (badblocks) on the given namespace
...