Apropos: A Powerful HELP command except man in Linux

Apropos: in Linux, man is a powerful HELP command except man. in Linux, man is always used, provided that you know how to write this command. What can I do if I want to complete a function but forget the specific command. You can directly enter apropos [keyword] to view the commands related to keyword. What this command actually completes is to search for the descriptions of other commands and list the relevant commands. Not necessarily the commands that appear are what you want, but can help you recall useful commands. Apropos Method man apropos. In the example of apropos, use apropos to search for sort-related commands: apropos sort alphasort [scandir] (3)-scan a directory for matching entriesbsearch (3) -binary search of a sorted arraybsearch (3 p)-binary search a sorted tablebunzip2 (1)-a block-sorting file compressor, v1.0.2bunzip2 [bzcat] (1) -a block-sorting file compressor, v1.0.2bunzip2 [bzip2] (1)-a block-sorting file compressor, v1.0.2bunzip2 [bzip2recover] (1)-a block-sorting file compressor, v1.0.2bzip2 (1)-a block-sorting file compressor, v1.0.2bzip2 [bunzip2] (1)-a block-sorting file compressor, v1.0.2bzip2 [bzcat] (1) -a block-sorting file compressor, v1.0.2bzip2 [bzip2recover] (1)-a block-sorting file compressor, v1.0.2comm (1) -compare two sorted files line by lineiterator_info_s [netsnmp_iterator_info_s] (3) -Holds iterator information containing functions which shold be called by the iterator_handler to loop over your data set and sort it in a SNMP specific mannerldap_sort_entries (3)-LDAP sorting tables [ldap_sort] (3) -LDAP sorting sort [ldap_sort_strcasecmp] (3)-LDAP sorting routinesldap_sort_entries [ldap_sort_values] (3)-LDAP sorting sort (3)-LDAP sorting sort [ldap_sort) -LDAP sorting indexes [ldap_sort_entries] (3)-LDAP sorting indexes [ldap_sort_values] (3)-LDAP sorting indexes (3)-LDAP sorting routinesldap_sort_values [ldap_sort] (3) -LDAP sorting Sort [ldap_sort_entries] (3)-LDAP sorting Sort [ldap_sort_strcasecmp] (3)-LDAP sorting routineslsort (n)-Sort the elements of a listqsort (3) -sorts an arrayqsort (3 p)-sort a table of datasort (1)-sort lines of text filessort (1 p)-sort, merge, or sequence check text filessort (3)-perl pragma to control sort () behaviourtexindex (1)-sort Texinfo index filestsort (1)-perform topological sorttsort (1 p) -topological sortuniq (1)-remove duplicate lines from a sorted fileversionsort [scandir] (3)-scan a directory for matching entries