Preface
Introduction
Practice Setup
Linux Architecture
Basic Commands
Basic file management or operations on file
User administration
Networking
Linux Interview Questions

 

 

Man, info and help commands

Man: It stands for manual. It gives the description about the commands. If you want to learn about any command

$ man ls

 

The above example will give the explanation about the command which is followed by man command. Along with the description, it also mentions about the options the command. The sections for commands are typically something like

  • Name of the command
  • Its synoptic
  • Its detailed description
  • Commands options
  • The author
  • Bugs of the command
  • Copyright
  • Commands history
  • See also ( related topics)

 

mint@mint ~ $ man ls[]

 

LS(1)                              user commands
                   LS(1)                                              
NAME
                ls -  list directory contents

SYNOPSIS

 ls   [OPTION]. . . [FILE]. . .

DESCRIPTION
              List information about the FILEs (the current directory by default) .
              Sort entries  alphabetically  if none of

              -cftuvSUX    nor - -sort.

              Mandatory  arguments  to  long  options are mandatory  for short options  too.
              -a.  - -all
                    do not  ignore entries  starting with .
              -A,    - -almost-all
                    do not  list implied .  and . .
              - -author

 

 

info command

  •  This command works like man command for linking pages.
mint@mint  ~$
mint@mint  ~$  info  ls[]
[F]ile: coreutils.info,     Node:  Is  invocation,      Next: dir invocation,      Up: Directory listing
10.1 ` Is':  list directory contents
==========================
The  'Is'  program lists information about files (of any tYpe, including directories).
Options and file arguments can be intermixed arbitrarily, as usual.
 
           For non-option command-line  arguments  that  are directories, by default  'Is'  lists the contents of directories, not recursively,  and omitting files with names beginning  with '.'.  For other non-option arguments,  by default  `Is ' lists just  the file name.  If no non-option argument  is specified, 'ls' operates on the current  directory,  acting as if it had been invoked with a single argument of ` .' .
         
          By default, the output  is sorted alphabetically, according to the locale settings in effect . (1) If standard output is a terminal, the output is in columns (sorted vertically) and control characters are output as question marks;  otherwise,  the output is listed one per line and control characters are output as-is.  
         
          Because 'Is'  is such a fundamental program, it has accumulated many options  over the years. They are described in the subsections below;  within each section. options are listed alphabetically (ignoring case).

 

Options :

 $ info –k <command>

 

   mint@mint  ~ $  info -k cat
 "(coreutils)General  output  formatting" - -  - -indicator-style
 "(coreutils)od  invocation" - -  - -output-duplicates
 "(coreutils)cat invocation" - - cat
 "(coreutils)cat invocation"  - - concatenate and write files
 "(coreutils)what information is listed" - - disk allocation
 "(coreutils)Modified command invocation"- - invocation of commands, modified
 "(coreutils)Sorting the output" - - modification time, sorting files by  
 "(coreutils)Modified command invocation"  - - modified command invocation
 "(coreutils)Numeric expressions" - - multiplication
 "(coreutils)chmod  invocation" - -  root directory, allow recursive modification <1>
 "(coreutils) chgrp invocation"  - - root directory,  allow recursive modification <2>
 "(coreutils)chown invocation" - - root directory, allow recursive modification
 "(coreutils)chmod invocation" - - root directory, disallow recursive modification <1>
 "(coreutils)chgrp invocation" -- root directory, disallow recursive modification <2>
 "(coreutils)chown invocation" - - root directory, disallow recursive modification
 "(coreutils)truncate invocation" - - truncate
 "-(coreutils)dd invocation"- - truncating output file, avoiding
 "(coreutils)truncate invocation" - - truncating, file sizes
 "(ssip)why Events Notification" - -  Why Events Notification
 "(ssip)Events  Notifications in SSIp"  - - Events Notifications in SSIP
 "(ssip)Switching  Notifications On and Off" - - Switching Notifications On and Off
 "(speech-dispatcher) Event Notification and Index marking in C" - - spd_set_notifi cation
 "(speech-dispatcher)Event  Notification and Index marking in C" - -  spd_set_notifi cation _off
 "(Speech-dispatcher)Event  Notification and Index marking in C" - -  spd_set_notification

look up STRING in all indices of all manuals.

 

$ -d--directory=DIR


add DIR to INFOPATH.

 

 

$ --dribble=FILENAME


remember user keystrokes in FILENAME.

 

 

$ -f--file=FILENAME


specify Info file to visit.

 

 

$ -h--help

 

mint@mint  ~ $ info  -h
Usage:  info [OpTION]...  [MENU-ITEM... ]
Read documentation in Info format.
Options:
-k,  --aproposoSTRING                look up STRING in all indices of all manuals.
-d,  --directory=DIR                 add DIR to INFOPATN.
     --dribble=FILENAME              remember user keystrokes in FILENAME.
-f,  --file=FILENAME                 specify Info file to visit.
-h,  --help                          display this help and exit.   
     --index-search=STRING           go to node pointed by index entry STRING.
-n,  --node=NODENAME                 specify nodes in first visited Info file.
-o,  --output=FliENAME               output selected nodes to FILENAME.   
--R, --raw-escapes                   Output  "raw" ANSI escapes (default).
     --no -raw-escapes               output escapes as literal text.
     --restore=FILENAM               read initial keystrokes from FILENAME. 
 -0. --show-options,   --usage       go to command-tine options node.
     --subnodes                      recursively output menu items.
     --vi-keys                       use vi-like and less-like key bindings.                                      
     --version                       display version information and exit.                        
-w,  --where,       --location       print physical location of Info file.
 
The first non-option argument.  if present,  is the menu entry to start from:  
it is searched for in all 'dir' files along INFOPATH.  
If it is not present, info merges all  'dir' files and shoot the result .
any remaining arguments are treated as the names of menu
items relative to the initial node visited.

For a summary of key bindings, type h within Info.


display this help and exit.

 

 

$ -index-search=STRING

 
go to the node pointed by index entry STRING.

 

 

$ -n--node=NODENAME


specify nodes in first visited Info file.

 

 

$ -o--output=FILENAME


output selected nodes to FILENAME.

 

 

-R--raw-escapes


output "raw" ANSI escapes (default).

 

 

$ --no-raw-escapes


output escapes as literal text.

 

 

$ --restore=FILENAME


read initial keystrokes from FILENAME.

 

 

$ -O--show-options--usage


go to command-line options node.