Chapter 4: Shell Builtin Commands

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contents of the readline editing buffer. If not set, Bash attempts to preserve what the user typed. dirspell

If set, Bash attempts spelling correction on directory names during word completion if the directory name initially supplied does not exist. dotglob

If set, Bash includes filenames beginning with a ‘.’ in the results of filename expansion. execfail

If this is 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 below under Aliases,

Section 6.6 [Aliases], page 88. 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 (see Section 4.2 [Bash

Builtins], page 48) displays the source file name and line num- ber corresponding to each function name supplied as an argu- ment.

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 (see Section 5.2 [Bash Variables], page 69).

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 func- tions, and subshells invoked with ( command ) inherit the ERR trap. extglob

If set, the extended pattern matching features described above (see

Section 3.5.8.1 [Pattern Matching], page 30) 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 filename ex- pansion 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