variables: variables - Names and meanings of some shell variables

Common shell variable names and usage.

    BASH_VERSION        Version information for this Bash.
    CDPATH      A colon-separated list of directories to search
                for directories given as arguments to `cd'.
    GLOBIGNORE  A colon-separated list of patterns describing filenames to
                be ignored by pathname expansion.
    HISTFILE    The name of the file where your command history is stored.
    HISTFILESIZE        The maximum number of lines this file can contain.
    HISTSIZE    The maximum number of history lines that a running
                shell can access.
    HOME        The complete pathname to your login directory.

HOSTNAME The name of the current host. HOSTTYPE The type of CPU this version of Bash is running under. IGNOREEOF Controls the action of the shell on receipt of an EOF

                character as the sole input.  If set, then the value
                of it is the number of EOF characters that can be seen
                in a row on an empty line before the shell will exit
                (default 10).  When unset, EOF signifies the end of input.

MACHTYPE A string describing the current system Bash is running on. MAILCHECK How often, in seconds, Bash checks for new mail. MAILPATH A colon-separated list of filenames which Bash checks

                for new mail.
    OSTYPE      The version of Unix this version of Bash is running on.
    PATH        A colon-separated list of directories to search when
                looking for commands.
    PROMPT_COMMAND      A command to be executed before the printing of each
                primary prompt.
    PS1         The primary prompt string.
    PS2         The secondary prompt string.
    PWD         The full pathname of the current directory.
    SHELLOPTS   A colon-separated list of enabled shell options.
    TERM        The name of the current terminal type.
    TIMEFORMAT  The output format for timing statistics displayed by the
                `time' reserved word.
    auto_resume Non-null means a command word appearing on a line by
                itself is first looked for in the list of currently
                stopped jobs.  If found there, that job is foregrounded.
                A value of `exact' means that the command word must
                exactly match a command in the list of stopped jobs.  A
                value of `substring' means that the command word must
                match a substring of the job.  Any other value means that
                the command must be a prefix of a stopped job.
    histchars   Characters controlling history expansion and quick
                substitution.  The first character is the history
                substitution character, usually `!'.  The second is
                the `quick substitution' character, usually `^'.  The
                third is the `history comment' character, usually `#'.
    HISTIGNORE  A colon-separated list of patterns used to decide which
                commands should be saved on the history list.