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Engineering LibreTexts

01-C.23: Additional Linux System Help Choices

  • Page ID
  • Other Helping Commands

    Linux has commands that provide additional choices for a user to find assistance with finding and using commands from the CLI.

    Choice Description Example
    info In addition to the man pages, you can read the Info pages about a command, using the info command. These usually contain more recent information and are somewhat easier to use. The man pages for some commands refer to the Info pages. The info command at times refers to the man pages.

    info - prints default page

    info info - opens info page about how to use info

    info man - depends on the distro - but usually opens the same page as man man command.

    apropos This command searches the NAME section of the man pages for the keyword the user enters. The output is the one line in the name section, but it also includes which section of the man pages is the command found in. pbmac@pbmac-server $ apropos email
    gpgparsemail (1) - Parse a mail message into an annotated format
    mailto.conf (5) - configuration file for cups email notifier
    nautilus-sendto (1) - convenience application to send a file via email
    uuencode (1) - encode a file into email friendly text
    X509_check_email (3ssl) - X.509 certificate matching
    X509_VERIFY_PARAM_set1_email (3ssl) - X509 verification parameters
    xdg-email (1) - command line tool for sending mail using the...
    whatis This command behaves similar to apropos, but it gives you the command, and what it does. You would use this command if you know a command name, but you are wanting to figure out what the command does. pbmac@pbmac-server $ whatis ls
    ls (1) - list directory contents
    pbmac@pbmac-server $ whatis cat
    cat (1) - concatenate files and print on the standard output
    --help Many of the Linux commands have been updated to include a --help option. The user simply enters the command in question followed by this option. Often the output is quite verbose.

    A partial output example:

    pbmac@pbmac-server $ cat --help
    Usage: cat [OPTION]... [FILE]...
    Concatenate FILE(s) to standard output.

    With no FILE, or when FILE is -, read standard input.

    -A, --show-all equivalent to -vET
    -b, --number-nonblank number nonempty output lines, overrides -n
    -e equivalent to -vE

    /usr/share/doc/ The files and subdirectories contain a lot of additional documentation for libraries, system libraries and other software packages installed on the system. There is not really a utility to read this documentation...using CLI commands like cat or less is how to do it. Some of the subdirectories contain README files, or other text files along with various gzipped files.
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