compgen

 

 

compgen is a shell builtin

 

1. compgen -u : display users
   

    

    

2. -a means Names of alias
   -b means Names of shell builtins
   -c means Names of all commands
   -d means Names of directory
   -e means Names of exported shell variables
   -f means Names of file and functions
   -g means Names of groups
   -j means Names of job
   -k means Names of Shell reserved words
   -s means Names of service
   -u means Names of userAlias names
   -v means Names of shell variables

    

3. -A action = The action may be one of the following to generate a list of possible completions: (see links)
   -C command = Run command in a subshell and use its output as the list of completions.
   -F function = Run shell function in the current shell. Upon its return, retrieve the list of completions from the COMPREPLY array.
   -G globpat = The filename expansion pattern globpat is expanded to generate the possible completions.
   -P prefix = prefix is added at the beginning of each possible completion after all other options have been applied.
   -S suffix = suffix is appended to each possible completion after all other options have been applied.
   -W wordlist = The wordlist is split using the characters in the IFS special variable as delimiters, and each resultant word is expanded. The possible completions are the members of the resultant list which match the word being completed.
   -X filterpat = filterpat is a pattern as used for filename expansion. It is applied to the list of possible completions generated by the preceding options and arguments, and each completion matching filterpat is removed from the list. A leading ‘!’ in filterpat negates the pattern; in this case, any completion not matching filterpat is removed.