colon-separated list of patterns defining the set of file names to be ignored by file name expansion.
   GROUPS    An array variable containing the list of groups of which the current user is a member.
   histchars    Up to three characters which control history expansion, quick substitution, and tokenization .
   HISTCMD    The history number, or index in the history list, of the current command.
   HISTCONTROL    Defines whether a command is added to the history file.
   HISTFILE    The name of the file to which the command history is saved. The default value is ~/.bash_history .
   HISTFILESIZE    The maximum number of lines contained in the history file, defaults to 500.
   HISTIGNORE    A colon-separated list of patterns used to decide which command lines should be saved in the history list.
   HISTSIZE    The maximum number of commands to remember on the history list, default is 500.
   HOSTFILE    Contains the name of a file in the same format as /etc/hosts that should be read when the shell needs to complete a hostname.
   HOSTNAME    The name of the current host.
   HOSTTYPE    A string describing the machine Bash is running on.
   IGNOREEOF    Controls the action of the shell on receipt of an EOF character as the sole input.
   INPUTRC    The name of the Readline initialization file, overriding the default /etc/inputrc .
   LANG    Used to determine the locale category for any category not specifically selected with a variable starting with LC_ .
   LC_ALL    This variable overrides the value of LANG and any other LC_ variable specifying a locale category.
   LC_COLLATE    This variable determines the collation order used when sorting the results of file name expansion, and determines the behavior of range expressions, equivalence classes, and collating sequences within file name expansion and pattern matching.
   LC_CTYPE    This variable determines the interpretation of characters and the behavior of character classes within file name expansion and pattern matching.
   LC_MESSAGES    This variable determines the locale used to translate double-quoted strings preceded by a "$" sign.
   LC_NUMERIC    This variable determines the locale category used for number formatting.
   LINENO    The line number in the script or shell function currently executing.
   LINES    Used by the select built-in to determine the column length for printing selection lists.
   MACHTYPE    A string that fully describes the system type on which Bash is executing, in the standard GNU CPU-COMPANY-SYSTEM format.
   MAILCHECK    How often (in seconds) that the shell should check for mail in the files specified in the MAILPATH or MAIL variables.
   OLDPWD    The previous working directory as set by the cd built-in.
   OPTERR    If set to the value 1, Bash displays error messages generated by the getopts built-in.
   OSTYPE    A string describing the operating system Bash is running on.
   PIPESTATUS    An array variable containing a list of exit status values from the processes in the most recently executed foreground pipeline (which may contain only a single command).
   POSIXLY_CORRECT    If this variable is in the environment when bash starts, the shell enters POSIX mode.
   PPID    The process ID of the shell's parent process.
   PROMPT_COMMAND    If set, the value is interpreted as