shopt Options

B.6 shopt Options

The shopt options are set with shopt -s arg and unset with shopt -u arg . See Table 2.7 for options to shopt . Versions of bash prior to 2.0 had environment variables to perform some of these settings. Setting them equated to shopt -s .

The variables (and corresponding shopt options) were: allow_null_glob_expansion ( nullglob ), cdable_vars ( cdable_vars ), command_oriented_history ( cmdhist ), glob_dot_filenames ( dotglob ), no_exit_on_failed_exec ( execfail ). These variables no longer exist.

Table B.7. Options to shopt


Meaning if Set


An argument to cd that is not a directory is assumed to be the name of a variable whose value is the directory to change to.


Minor errors in the spelling of a directory supplied to the cd command will be corrected if there is a suitable match. This correction includes missing letters, incorrect letters , and letter transposition. It works for interactive shells only.


Commands found in the hash table are checked for existence before being executed and non-existence forces a PATH search.


Checks the window size after each command and, if it has changed, updates the variables LINES and COLUMNS accordingly .


Attempt to save all lines of a multiline command in a single history entry.


Filenames beginning with a . are included in pathname expansion.


A non-interactive shell will not exit if it cannot execute the argument to an exec . Interactive shells do not exit if exec fails.


Aliases are expanded.


The history list is appended to the file named by the value of the variable HISTFILE when the shell exits, rather than overwriting the file.


If readline is being used, the opportunity is given for re-editing a failed history substitution.


If readline is being used, the results of history substitution are not immediately passed to the shell parser. Instead, the resulting line is loaded into the readline editing buffer, allowing further modification.


If readline is being used, an attempt will be made to perform hostname completion when a word beginning with @ is being completed.


Allows a word beginning with # and all subsequent characters on the line to be ignored in an interactive shell.


If the cmdhist option is enabled, multiline commands are saved to the history with embedded newlines rather than using semicolon separators where possible.


If the file being checked for mail has been accessed since the last time it was checked, the message "The mail in mailfile has been read" is displayed.


Allows patterns which match no files to expand to null strings rather than themselves .


Prompt strings undergo variable and parameter expansion after being expanded.


The shift built-in prints an error if it has shifted past the last positional parameter.


The source built-in uses the value of PATH to find the directory containing the file supplied as an argument.


Learning the Bash Shell
Learning the bash Shell: Unix Shell Programming (In a Nutshell (OReilly))
ISBN: 0596009658
EAN: 2147483647
Year: 1998
Pages: 104

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