Set shell options - toggle the value of variables which control optional shell behavior.
Syntax
shopt [-pqsu] [-o] [optname ...]
Key
-s Enable (set) each optname.
-u Disable (unset) each optname.
-q Suppress normal output (quiet mode); the return status indicates whether the optname
is set or unset.
-o Restrict the values of optname to be those defined for set -o.
Options:
cdable_vars
If set, an argument to the cd builtin command that is not a directory is assumed to be
the name of a variable whose value is the directory to change to.
cdspell If set, minor errors in the spelling of a directory component in a cd command will be
corrected. The errors checked for are transposed characters, a missing character, and
one character too many. If a correction is found, the corrected file name is printed,
and the command proceeds. This option is only used by interactive shells.
checkhash
If set, bash checks that a command found in the hash table exists before trying to
execute it. If a hashed command no longer exists, a normal path search is performed.
checkwinsize
If set, bash checks the window size after each command and, if necessary, updates the
values of LINES and COLUMNS.
cmdhist If set, bash attempts to save all lines of a multiple-line command in the same history
entry. This allows easy re-editing of multi-line commands.
dotglob If set, bash includes filenames beginning with a `.' in the results of pathname expansion.
execfail
If set, a non-interactive shell will not exit if it cannot execute the file specified
as an argument to the exec builtin command. An interactive shell does not exit if
exec fails.
expand_aliases
If set, aliases are expanded as described above under ALIASES. This option is enabled
by default for interactive shells.
extdebug
If set, behavior intended for use by debuggers is enabled:
1. The -F option to the declare builtin displays the source file name and line
number corresponding to each function name supplied as an argument.
2. If the command run by the DEBUG trap returns a non-zero value, the next command
is skipped and not executed.
3. If the command run by the DEBUG trap returns a value of 2, and the shell is
executing in a subroutine (a shell function or a shell script executed by the .
or source builtins), a call to return is simulated.
4. BASH_ARGC and BASH_ARGV are updated as described in their descriptions above.
5. Function tracing is enabled: command substitution, shell functions, and subshells
invoked with ( command ) inherit the DEBUG and RETURN traps.
6. Error tracing is enabled: command substitution, shell functions, and subshells
invoked with ( command ) inherit the ERROR trap.
extglob
If set, the extended pattern matching features described above under Pathname Expansion
are enabled.
extquote
If set, $'string' and $"string" quoting is performed within ${parameter} expansions
enclosed in double quotes. This option is enabled by default.
failglob
If set, patterns which fail to match filenames during pathname expansion result in an
expansion error.
force_fignore
If set, the suffixes specified by the FIGNORE shell variable cause words to be ignored
when performing word completion even if the ignored words are the only possible completions.
See SHELL VARIABLES for a description of FIGNORE. This option is enabled by default.
gnu_errfmt
If set, shell error messages are written in the standard GNU error message format.
histappend
If set, the history list is appended to the file named by the value of the HISTFILE
variable when the shell exits, rather than overwriting the file.
histreedit
If set, and readline is being used, a user is given the opportunity to re-edit a
failed history substitution.
histverify
If set, and 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.
hostcomplete
If set, and readline is being used, bash will attempt to perform hostname completion
when a word containing a @ is being completed (see Completing under READLINE).
This is enabled by default.
huponexit
If set, bash will send SIGHUP to all jobs when an interactive login shell exits.
interactive_comments
If set, allow a word beginning with # to cause that word and all remaining characters
on that line to be ignored in an interactive shell (see COMMENTS). This option
is enabled by default.
lithist If set, and the cmdhist option is enabled, multi-line commands are saved to the his-tory history
tory with embedded newlines rather than using semicolon separators where possible.
login_shell
The shell sets this option if it is started as a login shell (see INVOCATION).
The value may not be changed.
mailwarn
If set, and a file that bash is checking for mail has been accessed since the last
time it was checked, the message ``The mail in mailfile has been read'' is displayed.
no_empty_cmd_completion
If set, and readline is being used, bash will not attempt to search the PATH for pos-sible possible
sible completions when completion is attempted on an empty line.
nocaseglob
If set, bash matches filenames in a case-insensitive fashion when performing pathname
expansion (see Pathname Expansion).
nocasematch
If set, bash matches patterns in a case-insensitive fashion when performing matching
while executing case or [[ conditional commands.
nullglob
If set, bash allows patterns which match no files (see Pathname Expansion above) to
expand to a null string, rather than themselves.
progcomp
If set, the programmable completion facilities (see Programmable Completion above) are
enabled. This option is enabled by default.
promptvars
If set, prompt strings undergo parameter expansion, command substitution, arithmetic
expansion, and quote removal after being expanded as described in PROMPTING above.
This option is enabled by default.
restricted_shell
The shell sets this option if it is started in restricted mode (see RESTRICTED SHELL
below). The value may not be changed. This is not reset when the startup files are
executed, allowing the startup files to discover whether or not a shell is restricted.
shift_verbose
If set, the shift builtin prints an error message when the shift count exceeds the
number of positional parameters.
sourcepath
If set, the source (.) builtin uses the value of PATH to find the directory containing
the file supplied as an argument. This option is enabled by default.
xpg_echo
If set, the echo builtin expands backslash-escape sequences by default.
With no options, or with the -p option, a list of all settable options is displayed, with an indication of whether or not each is set.
The -p option causes output to be displayed in a form that may be reused as input.
If either -s or -u is used with no optname arguments, the display is limited to those options which are set or unset, respectively. Unless otherwise noted, the shopt options are disabled (unset) by default.
The return status when listing options is zero if all optnames are enabled, non-zero otherwise.
If multiple optname arguments are given with -q, the return status is
zero if all optnames are enabled; non-zero otherwise.
When setting or unsetting options, the return status is zero unless an optname is not a valid shell option.
shopt is a bash builtin command.
“Try to be like the turtle - at ease in your own shell” ~ Bill Copeland
set - Set a shell variable = value
unset - Remove variable or function names.