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diff --git a/doc/bash.html b/doc/bash.html index 983284e8..54b42fec 100644 --- a/doc/bash.html +++ b/doc/bash.html @@ -3,7 +3,7 @@ </HEAD> <BODY><TABLE WIDTH=100%> <TR> -<TH ALIGN=LEFT width=33%>BASH(1)<TH ALIGN=CENTER width=33%>2016 August 26<TH ALIGN=RIGHT width=33%>BASH(1) +<TH ALIGN=LEFT width=33%>BASH(1)<TH ALIGN=CENTER width=33%>2018 March 15<TH ALIGN=RIGHT width=33%>BASH(1) </TR> </TABLE> <BR><A HREF="#index">Index</A> @@ -42,7 +42,7 @@ bash - GNU Bourne-Again SHell <H3>COPYRIGHT</H3> -Bash is Copyright © 1989-2016 by the Free Software Foundation, Inc. +Bash is Copyright © 1989-2018 by the Free Software Foundation, Inc. <A NAME="lbAE"> </A> <H3>DESCRIPTION</H3> @@ -68,8 +68,8 @@ can be configured to be POSIX-conformant by default. <H3>OPTIONS</H3> All of the single-character shell options documented in the -description of the <B>set</B> builtin command can be used as options -when the shell is invoked. +description of the <B>set</B> builtin command, including <B>-o</B>, +can be used as options when the shell is invoked. In addition, <B>bash</B> interprets the following options when it is invoked: <P> @@ -139,7 +139,8 @@ If the option is present, or if no arguments remain after option processing, then commands are read from the standard input. This option allows the positional parameters to be set -when invoking an interactive shell. +when invoking an interactive shell or when reading input +through a pipe. <DT><B>-D</B> <DD> @@ -780,6 +781,12 @@ the time information. Each command in a pipeline is executed as a separate process (i.e., in a subshell). +See +<FONT SIZE=-1><B>COMMAND EXECUTION ENVIRONMENT</B></FONT> +for a description of a subshell environment. +If the <B>lastpipe</B> option is enabled using the <B>shopt</B> builtin +(see the description of <B>shopt</B> below), +the last element of a pipeline may be run by the shell process. <A NAME="lbAN"> </A> <H4>Lists</H4> @@ -855,7 +862,7 @@ An AND list has the form is executed if, and only if, <I>command1</I> -returns an exit status of zero. +returns an exit status of zero (success). <P> An OR list has the form @@ -871,7 +878,7 @@ An OR list has the form <I>command2</I> -is executed if and only if +is executed if, and only if, <I>command1</I> returns a non-zero exit status. @@ -1110,11 +1117,11 @@ or zero if no commands were executed. <DT><B>case</B> <I>word</I> <B>in</B> [ [(] <I>pattern</I> [ <B>|</B> <I>pattern</I> ] <DD> A <B>case</B> command first expands <I>word</I>, and tries to match -it against each <I>pattern</I> in turn, using the same matching rules -as for pathname expansion (see -<B>Pathname Expansion</B> +it against each <I>pattern</I> in turn, using the matching rules +described under +<B>Pattern Matching</B> -below). +below. The <I>word</I> is expanded using tilde expansion, parameter and variable expansion, arithmetic expansion, command substitution, process substitution and quote removal. @@ -1217,7 +1224,8 @@ command (see below). The file descriptors can be utilized as arguments to shell commands and redirections using standard word expansions. -The file descriptors are not available in subshells. +Other than those created to execute command and process substitutions, +the file descriptors are not available in subshells. The process ID of the shell spawned to execute the coprocess is available as the value of the variable <I>NAME</I>_PID. The <B>wait</B> @@ -1463,7 +1471,7 @@ question mark <DD> the eight-bit character whose value is the octal value <I>nnn</I> -(one to three digits) +(one to three octal digits) <DT><B>\x</B><I>HH</I> <DD> @@ -1868,6 +1876,16 @@ This variable is read-only. Expands to the process ID of the current <B>bash</B> process. This differs from <B>$$</B> under certain circumstances, such as subshells that do not require <B>bash</B> to be re-initialized. +Assignments to +<FONT SIZE=-1><B>BASHPID</B> + +</FONT> +have no effect. +If +<B>BASHPID</B> + +is unset, it loses its special properties, even if it is +subsequently reset. <DT><B>BASH_ALIASES</B> <DD> @@ -1903,7 +1921,9 @@ only when in extended debugging mode (see the description of the option to the <B>shopt</B> -builtin below) +builtin below). +Setting <B>extdebug</B> after the shell has started to execute a script +may result in inconsistent values. <DT><B>BASH_ARGV</B> <DD> @@ -1926,7 +1946,26 @@ only when in extended debugging mode option to the <B>shopt</B> -builtin below) +builtin below). +Setting <B>extdebug</B> after the shell has started to execute a script +may result in inconsistent values. +<DT><B>BASH_ARGV0</B> + +<DD> +When referenced, this variable expands to the name of the shell or shell +script (identical to +<B>$0</B>; + +see the description of special parameter 0 above). +Assignment to +<B>BASH_ARGV0</B> + +causes the value assigned to also be assigned to <B>$0</B>. +If +<B>BASH_ARGV0</B> + +is unset, it loses its special properties, even if it is +subsequently reset. <DT><B>BASH_CMDS</B> <DD> @@ -2155,6 +2194,39 @@ If </FONT> is unset, it loses its special properties, even if it is subsequently reset. +<DT><B>EPOCHREALTIME</B> + +<DD> +Each time this parameter is referenced, it expands to the number of seconds +since the Unix Epoch (see <I>time</I>(3)) as a floating point value +with micro-second granularity. +Assignments to +<FONT SIZE=-1><B>EPOCHREALTIME</B> + +</FONT> +are ignored. +If +<FONT SIZE=-1><B>EPOCHREALTIME</B> + +</FONT> +is unset, it loses its special properties, even if it is +subsequently reset. +<DT><B>EPOCHSECONDS</B> + +<DD> +Each time this parameter is referenced, it expands to the number of seconds +since the Unix Epoch (see <I>time</I>(3)). +Assignments to +<FONT SIZE=-1><B>EPOCHSECONDS</B> + +</FONT> +are ignored. +If +<FONT SIZE=-1><B>EPOCHSECONDS</B> + +</FONT> +is unset, it loses its special properties, even if it is +subsequently reset. <DT><B>EUID</B> <DD> @@ -2612,9 +2684,9 @@ will cause the current command to abort. <DT><B>GLOBIGNORE</B> <DD> -A colon-separated list of patterns defining the set of filenames to +A colon-separated list of patterns defining the set of file names to be ignored by pathname expansion. -If a filename matched by a pathname expansion pattern also matches one +If a file name matched by a pathname expansion pattern also matches one of the patterns in <FONT SIZE=-1><B>GLOBIGNORE</B>, @@ -3035,6 +3107,7 @@ and the value is printed before each command <B>bash</B> displays during an execution trace. The first character of +the expanded value of <FONT SIZE=-1><B>PS4</B> </FONT> @@ -3327,15 +3400,21 @@ The <B>unset</B> builtin is used to destroy arrays. <B>unset</B> <I>name</I>[<I>subscript</I>] -destroys the array element at index <I>subscript</I>. +destroys the array element at index <I>subscript</I>, +for both indexed and associative arrays. Negative subscripts to indexed arrays are interpreted as described above. -Care must be taken to avoid unwanted side effects caused by pathname -expansion. +Unsetting the last element of an array variable does not unset the variable. <B>unset</B> <I>name</I>, where <I>name</I> is an array, or <B>unset</B> <I>name</I>[<I>subscript</I>], where <I>subscript</I> is <B>*</B> or <B>@</B>, removes the entire array. <P> +When using a variable name with a subscript as an argument to a command, +such as with <B>unset</B>, without using the word expansion syntax +described above, the argument is subject to pathname expansion. +If pathname expansion is not desired, the argument should be quoted. +<P> + The <B>declare</B>, @@ -3413,10 +3492,11 @@ original word are removed unless they have been quoted themselves <P> Only brace expansion, word splitting, and pathname expansion -can change the number of words of the expansion; other expansions +can increase the number of words of the expansion; other expansions expand a single word to a single word. The only exceptions to this are the expansions of -"<B>$@</B>" and "<B>${</B><I>name</I><B>[@]}</B>" +"<B>$@</B>" and "<B>${</B><I>name</I><B>[@]}</B>", +and, in most cases, <B>$*</B> and <B>${</B><I>name</I><B>[*]}</B> as explained above (see <FONT SIZE=-1><B>PARAMETERS</B>). @@ -3485,7 +3565,8 @@ Any incorrectly formed brace expansion is left unchanged. A <B>{</B> or <B>,</B> may be quoted with a backslash to prevent its being considered part of a brace expression. To avoid conflicts with parameter expansion, the string <B>${</B> -is not considered eligible for brace expansion. +is not considered eligible for brace expansion, and inhibits brace +expansion until the closing <B>}</B>. <P> This construct is typically used as shorthand when the common @@ -3663,6 +3744,8 @@ it introduces a level of variable indirection. expanded and that value is used in the rest of the substitution, rather than the value of <I>parameter</I> itself. This is known as <I>indirect expansion</I>. +The value is subject to tilde expansion, +parameter expansion, command substitution, and arithmetic expansion. If <I>parameter</I> is a nameref, this expands to the name of the variable referenced by <I>parameter</I> instead of performing the complete indirect expansion. @@ -3848,7 +3931,14 @@ The <I>word</I> is expanded to produce a pattern just as in pathname -expansion. If the pattern matches the beginning of +expansion, and matched against the expanded value of +<I>parameter</I> + +using the rules described under +<B>Pattern Matching</B> + +below. +If the pattern matches the beginning of the value of <I>parameter</I>, @@ -3885,7 +3975,13 @@ array in turn, and the expansion is the resultant list. <B>Remove matching suffix pattern</B>. The <I>word</I> is expanded to produce a pattern just as in -pathname expansion. +pathname expansion, and matched against the expanded value of +<I>parameter</I> + +using the rules described under +<B>Pattern Matching</B> + +below. If the pattern matches a trailing portion of the expanded value of <I>parameter</I>, @@ -3919,9 +4015,13 @@ array in turn, and the expansion is the resultant list. <DT>${<I>parameter</I><B>/</B><I>pattern</I><B>/</B><I>string</I>}<DD> <B>Pattern substitution</B>. The <I>pattern</I> is expanded to produce a pattern just as in -pathname expansion. +pathname expansion, <I>Parameter</I> is expanded and the longest match of <I>pattern</I> against its value is replaced with <I>string</I>. +The match is performed using the rules described under +<B>Pattern Matching</B> + +below. If <I>pattern</I> begins with <B>/</B>, all matches of <I>pattern</I> are replaced with <I>string</I>. Normally only the first match is replaced. If <I>pattern</I> begins with <B>#</B>, it must match at the beginning @@ -4018,7 +4118,7 @@ format that can be reused as input. <DD> The expansion is a string that is the value of <I>parameter</I> with backslash -escape sequences expanded as with the <B>$'...'</B> quoting mechansim. +escape sequences expanded as with the <B>$'...'</B> quoting mechanism. <DT><B>P</B> <DD> @@ -4059,7 +4159,7 @@ is an array variable subscripted with or <B>*</B>, -the case modification operation is applied to each member of the +the operation is applied to each member of the array in turn, and the expansion is the resultant list. <P> The result of the expansion is subject to word splitting and pathname @@ -4354,12 +4454,27 @@ must be matched explicitly, unless the shell option <B>dotglob</B> is set. -When matching a pathname, the slash character must always be -matched explicitly. +The filenames +<B>``.''</B> + +and +<B>``..''</B> + +must always be matched explicitly, even if +<B>dotglob</B> + +is set. In other cases, the <B>``.''</B> character is not treated specially. +When matching a pathname, the slash character must always be +matched explicitly by a slash in the pattern, but in other matching +contexts it can be matched by a special pattern character as described +below under +<FONT SIZE=-1><B>Pattern Matching</B>. + +</FONT> See the description of <B>shopt</B> @@ -4384,14 +4499,14 @@ The <FONT SIZE=-1><B>GLOBIGNORE</B> </FONT> -shell variable may be used to restrict the set of filenames matching a +shell variable may be used to restrict the set of file names matching a <I>pattern</I>. If <FONT SIZE=-1><B>GLOBIGNORE</B> </FONT> -is set, each matching filename that also matches one of the patterns in +is set, each matching file name that also matches one of the patterns in <FONT SIZE=-1><B>GLOBIGNORE</B> </FONT> @@ -4613,6 +4728,13 @@ Matches anything except one of the given patterns </DL></DL> +<P> + +Complicated extended pattern matching against long strings is slow, +especially when the patterns contain alternations and the strings +contain multiple matches. +Using separate matches against shorter strings, or using arrays of +strings instead of a single long string, may be faster. <A NAME="lbBH"> </A> <H4>Quote Removal</H4> @@ -4659,6 +4781,9 @@ than or equal to 10 and assign it to <I>varname</I>. If >&- or <&- is preceded by {<I>varname</I>}, the value of <I>varname</I> defines the file descriptor to close. +If {<I>varname</I>} is supplied, the redirection persists beyond +the scope of the command, allowing the shell programmer to manage +the file descriptor himself. <P> In the following descriptions, if the file descriptor number is @@ -5035,7 +5160,7 @@ A variant of here documents, the format is: <P> The <I>word</I> undergoes -brace expansion, tilde expansion, parameter and variable expansion, +tilde expansion, parameter and variable expansion, command substitution, arithmetic expansion, and quote removal. Pathname expansion and word splitting are not performed. The result is supplied as a single string, with a newline appended, @@ -5339,6 +5464,47 @@ Variables local to the function may be declared with the builtin command. Ordinarily, variables and their values are shared between the function and its caller. +If a variable is declared <B>local</B>, the variable's visible scope +is restricted to that function and its children (including the functions +it calls). +Local variables "shadow" variables with the same name declared at +previous scopes. +For instance, a local variable declared in a function +hides a global variable of the same name: references and assignments +refer to the local variable, leaving the global variable unmodified. +When the function returns, the global variable is once again visible. +<P> + +The shell uses <I>dynamic scoping</I> to control a variable's visibility +within functions. +With dynamic scoping, visible variables and their values +are a result of the sequence of function calls that caused execution +to reach the current function. +The value of a variable that a function sees depends +on its value within its caller, if any, whether that caller is +the "global" scope or another shell function. +This is also the value that a local variable +declaration "shadows", and the value that is restored when the function +returns. +<P> + +For example, if a variable <I>var</I> is declared as local in function +<I>func1</I>, and <I>func1</I> calls another function <I>func2</I>, +references to <I>var</I> made from within <I>func2</I> will resolve to the +local variable <I>var</I> from <I>func1</I>, shadowing any global variable +named <I>var</I>. +<P> + +The <B>unset</B> builtin also acts using the same dynamic scope: if a +variable is local to the current scope, <B>unset</B> will unset it; +otherwise the unset will refer to the variable found in any calling scope +as described above. +If a variable at the current local scope is unset, it will remain so +until it is reset in that scope or until the function returns. +Once the function returns, any instance of the variable at a previous +scope will become visible. +If the unset acts on a variable at a previous scope, any instance of a +variable with that name that had been shadowed will become visible. <P> The <B>FUNCNEST</B> variable, if set to a numeric value greater @@ -5397,10 +5563,6 @@ the <B>unset</B> builtin. -Note that shell functions and variables with the same name may result -in multiple identically-named entries in the environment passed to the -shell's children. -Care should be taken in cases where this may cause a problem. <P> Functions may be recursive. @@ -5742,6 +5904,17 @@ and <I>arg2</I> may be positive or negative integers. +When used with the <B>[[</B> command, +<I>Arg1</I> + +and +<I>Arg2</I> + +are evaluated as arithmetic expressions (see +<FONT SIZE=-1><B>ARITHMETIC EVALUATION</B> + +</FONT> +above). </DL> <A NAME="lbBX"> </A> @@ -5834,9 +6007,10 @@ A full search of the directories in is performed only if the command is not found in the hash table. If the search is unsuccessful, the shell searches for a defined shell function named <B>command_not_found_handle</B>. -If that function exists, it is invoked with the original command and +If that function exists, it is invoked in a separate execution environment +with the original command and the original command's arguments as its arguments, and the function's -exit status becomes the exit status of the shell. +exit status becomes the exit status of that subshell. If that function is not defined, the shell prints an error message and returns an exit status of 127. <P> @@ -6427,6 +6601,12 @@ command may then be used to inspect their status. If a second attempt to exit is made without an intervening command, the shell does not print another warning, and any stopped jobs are terminated. +<P> + +When the shell is waiting for a job or process using the <B>wait</B> +builtin, and job control is enabled, <B>wait</B> will return when the +job changes state. The <B>-f</B> option will force <B>wait</B> to wait +until the job or process terminates before returning. <A NAME="lbCE"> </A> <H3>PROMPTING</H3> @@ -6445,11 +6625,20 @@ when it needs more input to complete a command. <B>Bash</B> displays -<B>PS0</B> +<FONT SIZE=-1><B>PS0</B> +</FONT> after it reads a command but before executing it. <B>Bash</B> +displays +<FONT SIZE=-1><B>PS4</B> + +</FONT> +as described above +before tracing each command when the <B>-x</B> option is enabled. +<B>Bash</B> + allows these prompt strings to be customized by inserting a number of backslash-escaped special characters that are decoded as follows: <DL COMPACT><DT><DD> @@ -7134,6 +7323,17 @@ can be set to either or <B>vi</B>. +<DT><B>emacs-mode-string (@)</B> + +<DD> +If the <I>show-mode-in-prompt</I> variable is enabled, +this string is displayed immediately before the last line of the primary +prompt when emacs editing mode is active. The value is expanded like a +key binding, so the standard set of meta- and control prefixes and +backslash escape sequences is available. +Use the \1 and \2 escapes to begin and end sequences of +non-printing characters, which can be used to embed a terminal control +sequence into the mode string. <DT><B>enable-bracketed-paste (Off)</B> <DD> @@ -7217,16 +7417,6 @@ the value of <B>editing-mode</B> also affects the default keymap. -<DT><B>emacs-mode-string (@)</B> - -<DD> -This string is displayed immediately before the last line of the primary -prompt when emacs editing mode is active. The value is expanded like a -key binding, so the standard set of meta- and control prefixes and -backslash escape sequences is available. -Use the \1 and \2 escapes to begin and end sequences of -non-printing characters, which can be used to embed a terminal control -sequence into the mode string. <DT><B>keyseq-timeout (500)</B> <DD> @@ -7320,9 +7510,9 @@ of ringing the bell. <DT><B>show-mode-in-prompt (Off)</B> <DD> -If set to <B>On</B>, add a character to the beginning of the prompt -indicating the editing mode: emacs (@), vi command (:) or vi -insertion (+). +If set to <B>On</B>, add a string to the beginning of the prompt +indicating the editing mode: emacs, vi command, or vi insertion. +The mode strings are user-settable (e.g., <I>emacs-mode-string</I>). <DT><B>skip-completed-text (Off)</B> <DD> @@ -7335,7 +7525,8 @@ following the cursor are not duplicated. <DT><B>vi-cmd-mode-string ((cmd))</B> <DD> -This string is displayed immediately before the last line of the primary +If the <I>show-mode-in-prompt</I> variable is enabled, +this string is displayed immediately before the last line of the primary prompt when vi editing mode is active and in command mode. The value is expanded like a key binding, so the standard set of meta- and control prefixes and @@ -7346,7 +7537,8 @@ sequence into the mode string. <DT><B>vi-ins-mode-string ((ins))</B> <DD> -This string is displayed immediately before the last line of the primary +If the <I>show-mode-in-prompt</I> variable is enabled, +this string is displayed immediately before the last line of the primary prompt when vi editing mode is active and in insertion mode. The value is expanded like a key binding, so the standard set of meta- and control prefixes and @@ -7378,8 +7570,9 @@ The construct allows bindings to be made based on the editing mode, the terminal being used, or the application using -readline. The text of the test extends to the end of the line; -no characters are required to isolate it. +readline. The text of the test, after any comparison operator, +<BR> extends to the end of the line; +unless otherwise noted, no characters are required to isolate it. <DL COMPACT><DT><DD> <DL COMPACT> <DT><B>mode</B><DD> @@ -7406,6 +7599,33 @@ and <I>sun-cmd</I>, for instance. +<DT><B>version</B><DD> +The <B>version</B> test may be used to perform comparisons against +specific readline versions. +The <B>version</B> expands to the current readline version. +The set of comparison operators includes +<B>=</B>, + +(and +<B>==</B>), + +<B>!=</B>, + +<B><=</B>, + +<B>>=</B>, + +<B><</B>, + +and +<B>></B>. + +The version number supplied on the right side of the operator consists +of a major version number, an optional decimal point, and an optional +minor version (e.g., <B>7.1</B>). If the minor version is omitted, it +is assumed to be <B>0</B>. +The operator may be separated from the string <B>version</B> +and from the version number argument by whitespace. <DT><B>application</B><DD> The <B>application</B> construct is used to include application-specific settings. Each program using the readline @@ -7425,6 +7645,15 @@ key sequence that quotes the current or previous word in <B>bash</B>: </DL> +<DT><I>variable</I><DD> +The <I>variable</I> construct provides simple equality tests for readline +variables and values. +The permitted comparison operators are <I>=</I>, <I>==</I>, and <I>!=</I>. +The variable name must be separated from the comparison operator by +whitespace; the operator may be separated from the value on the right hand +side by whitespace. +Both string and boolean variables may be tested. Boolean variables must be +tested against the values <I>on</I> and <I>off</I>. </DL></DL> <DT><B>$endif</B><DD> @@ -7554,6 +7783,21 @@ Words are delimited by non-quoted shell metacharacters. <DD> Move back to the start of the current or previous word. Words are delimited by non-quoted shell metacharacters. +<DT><B>previous-screen-line</B> + +<DD> +Attempt to move point to the same physical screen column on the previous +physical screen line. This will not have the desired effect if the current +Readline line does not take up more than one physical line or if point is not +greater than the length of the prompt plus the screen width. +<DT><B>next-screen-line</B> + +<DD> +Attempt to move point to the same physical screen column on the next +physical screen line. This will not have the desired effect if the current +Readline line does not take up more than one physical line or if the length +of the current Readline line is not greater than the length of the prompt +plus the screen width. <DT><B>clear-screen (C-l)</B> <DD> @@ -7634,6 +7878,21 @@ This is a non-incremental search. Search backward through the history for the string of characters between the start of the current line and the point. This is a non-incremental search. +<DT><B>history-substring-search-backward</B> + +<DD> +Search backward through the history for the string of characters +between the start of the current line and the current cursor +position (the <I>point</I>). +The search string may match anywhere in a history line. +This is a non-incremental search. +<DT><B>history-substring-search-forward</B> + +<DD> +Search forward through the history for the string of characters +between the start of the current line and the point. +The search string may match anywhere in a history line. +This is a non-incremental search. <DT><B>yank-nth-arg (M-C-y)</B> <DD> @@ -7710,9 +7969,10 @@ A synonym for <B>yank-last-arg</B>. <DD> Accept the current line for execution and fetch the next line -relative to the current line from the history for editing. Any -argument is ignored. -<DT><B>edit-and-execute-command (C-xC-e)</B> +relative to the current line from the history for editing. +A numeric argument, if supplied, specifies the history entry to use instead +of the current line. +<DT><B>edit-and-execute-command (C-x C-e)</B> <DD> Invoke an editor on the current command line, and execute the result as shell @@ -8124,11 +8384,12 @@ Abort the current editing command and ring the terminal's bell (subject to the setting of <B>bell-style</B>). -<DT><B>do-uppercase-version (M-a, M-b, M-</B><I>x</I>, ...) +<DT><B>do-lowercase-version (M-A, M-B, M-</B><I>x</I>, ...) <DD> -If the metafied character <I>x</I> is lowercase, run the command -that is bound to the corresponding uppercase character. +If the metafied character <I>x</I> is uppercase, run the command +that is bound to the corresponding metafied lowercase character. +The behavior is undefined if <I>x</I> is already lowercase. <DT><B>prefix-meta (ESC)</B> <DD> @@ -8542,7 +8803,7 @@ If <B>HISTFILESIZE</B> is unset, or set to null, a non-numeric value, or a numeric value less than zero, the history file is not truncated. When the history file is read, lines beginning with the history comment character followed immediately -by a digit are interpreted as timestamps for the preceding history line. +by a digit are interpreted as timestamps for the following history line. These timestamps are optionally displayed depending on the value of the <FONT SIZE=-1><B>HISTTIMEFORMAT</B> @@ -8652,7 +8913,7 @@ for information on setting and unsetting shell options. The shell supports a history expansion feature that is similar to the history expansion in -<B>csh.</B> +<B>csh</B>. This section describes what syntax features are available. This feature is enabled by default for interactive shells, and can be @@ -8677,7 +8938,9 @@ fix errors in previous commands quickly. <P> History expansion is performed immediately after a complete line -is read, before the shell breaks it into words. +is read, before the shell breaks it into words, and is performed +on each line individually without taking quoting on previous lines into +account. It takes place in two parts. The first is to determine which line from the history list to use during substitution. @@ -9035,7 +9298,7 @@ accepts <B>--</B> to signify the end of the options. -The <B>:</B>, <B>true</B>, <B>false</B>, and <B>test</B> builtins +The <B>:</B>, <B>true</B>, <B>false</B>, and <B>test</B>/<B>[</B> builtins do not accept options and do not treat <B>--</B> specially. The <B>exit</B>, <B>logout</B>, <B>return</B>, <B>break</B>, <B>continue</B>, <B>let</B>, @@ -9705,6 +9968,13 @@ The <I>wordlist</I> is split using the characters in the </FONT> special variable as delimiters, and each resultant word is expanded. +Shell quoting is honored within <I>wordlist</I>, +in order to provide a +mechanism for the words to contain shell metacharacters or characters +in the value of +<FONT SIZE=-1><B>IFS</B>. + +</FONT> The possible completions are the members of the resultant list which match the word being completed. <DT><B>-X</B> <I>filterpat</I><DD> @@ -10209,6 +10479,7 @@ unless the shell option is enabled. In that case, it returns failure. An interactive shell returns failure if the file cannot be executed. +A subshell exits unconditionally if <B>exec</B> fails. If <I>command</I> @@ -10292,7 +10563,7 @@ where a negative number is used as an offset from the current command number). If <I>last</I> -is not specified it is set to +is not specified, it is set to the current command for listing (so that <TT>fc -l -10</TT> @@ -10303,7 +10574,7 @@ otherwise. If <I>first</I> -is not specified it is set to the previous +is not specified, it is set to the previous command for editing and -16 for listing. <P> The @@ -10349,7 +10620,7 @@ echoed and executed. <P> In the second form, <I>command</I> is re-executed after each instance of <I>pat</I> is replaced by <I>rep</I>. -<I>Command</I> is intepreted the same as <I>first</I> above. +<I>Command</I> is interpreted the same as <I>first</I> above. A useful alias to use with this is <TT>r='fc -s'</TT>, @@ -10621,6 +10892,7 @@ The return status is 0 unless no command matches <DT><B>history</B> <B>-c</B><DD> <DT><B>history -d</B> <I>offset</I><DD> +<DT><B>history -d</B> <I>start</I>-<I>end</I><DD> <DT><B>history</B> <B>-anrw</B> [<I>filename</I>]<DD> <DT><B>history</B> <B>-p</B> <I>arg</I> [<I>arg ...</I>]<DD> <DT><B>history</B> <B>-s</B> <I>arg</I> [<I>arg ...</I>]<DD> @@ -10661,6 +10933,14 @@ is used. Options, if supplied, have the following meanings: Clear the history list by deleting all the entries. <DT><B>-d</B> <I>offset</I><DD> Delete the history entry at position <I>offset</I>. +If <I>offset</I> is negative, it is interpreted as relative to one greater +than the last history position, so negative indices count back from the +end of the history, and an index of -1 refers to the current +<B>history -d</B> command. +<DT><B>-d</B> <I>start</I>-<I>end</I><DD> +Delete the history entries between positions <I>start</I> and <I>end</I>, +inclusive. Positive and negative values for <I>start</I> and <I>end</I> +are interpreted as described above. <DT><B>-a</B> <DD> @@ -10935,6 +11215,8 @@ Options, if supplied, have the following meanings: <DD> The first character of <I>delim</I> is used to terminate each input line, rather than newline. +If <I>delim</I> is the empty string, <B>mapfile</B> will terminate a line +when it reads a NUL character. <DT><B>-n</B> <DD> @@ -11250,6 +11532,8 @@ Other <I>name</I> arguments are ignored. <DD> The first character of <I>delim</I> is used to terminate the input line, rather than newline. +If <I>delim</I> is the empty string, <B>read</B> will terminate a line +when it reads a NUL character. <DT><B>-e</B> <DD> @@ -11263,7 +11547,7 @@ is coming from a terminal, </FONT> above) is used to obtain the line. Readline uses the current (or default, if line editing was not previously -active) editing settings. +active) editing settings, but uses Readline's default filename completion. <DT><B>-i </B><I>text</I> <DD> @@ -11409,7 +11693,7 @@ is omitted, the return status is that of the last command executed in the function body. If <B>return</B> is executed by a trap handler, the last command used to determine the status is the last command executed before the trap handler. -if <B>return</B> is executed during a <B>DEBUG</B> trap, the last command +If <B>return</B> is executed during a <B>DEBUG</B> trap, the last command used to determine the status is the last command executed by the trap handler before <B>return</B> was invoked. If @@ -11970,7 +12254,8 @@ With no options, or with the <B>-p</B> option, a list of all settable options is displayed, with -an indication of whether or not each is set. +an indication of whether or not each is set; +if <I>optnames</I> are supplied, the output is restricted to those options. The <B>-p</B> option causes output to be displayed in a form that may be reused as input. Other options have the following meanings: @@ -12035,6 +12320,12 @@ The list of <B>shopt</B> options is: <DL COMPACT> +<DT><B>assoc_expand_once</B> + +<DD> +If set, the shell suppresses multiple evaluation of associative array +subscripts during arithmetic expression evaluation and while executing +builtins that can perform variable assignments. <DT><B>autocd</B> <DD> @@ -12083,8 +12374,8 @@ postpones exiting if any jobs are stopped. <DT><B>checkwinsize</B> <DD> -If set, <B>bash</B> checks the window size after each command -and, if necessary, updates the values of +If set, <B>bash</B> checks the window size after each external (non-builtin) +command and, if necessary, updates the values of <FONT SIZE=-1><B>LINES</B> </FONT> @@ -12101,6 +12392,11 @@ If set, attempts to save all lines of a multiple-line command in the same history entry. This allows easy re-editing of multi-line commands. +This option is enabled by default, but only has an effect if command +history is enabled, as described above under +<FONT SIZE=-1><B>HISTORY</B>. + +</FONT> <DT><B>compat31</B> <DD> @@ -12175,6 +12471,14 @@ to make them fatal errors that cause the shell to exit), and does not reset the loop state when a shell function is executed (this allows <B>break</B> or <B>continue</B> in a shell function to affect loops in the caller's context). +<DT><B>compat44</B> + +<DD> +If set, +<B>bash</B> + +saves the positional parameters to BASH_ARGV and BASH_ARGC before they are +used, regardless of whether or not extended debugging mode is enabled. <DT><B>complete_fullquote</B> <DD> @@ -12226,6 +12530,16 @@ If set, includes filenames beginning with a `.' in the results of pathname expansion. +The filenames +<B>``.''</B> + +and +<B>``..''</B> + +must always be matched explicitly, even if +<B>dotglob</B> + +is set. <DT><B>execfail</B> <DD> @@ -12441,6 +12755,12 @@ If set, and the option is enabled, multi-line commands are saved to the history with embedded newlines rather than using semicolon separators where possible. +<DT><B>localvar_inherit</B> + +<DD> +If set, local variables inherit the value and attributes of a variable of +the same name that exists at a previous scope before any new value is +assigned. The nameref attribute is not inherited. <DT><B>login_shell</B> <DD> @@ -13221,22 +13541,25 @@ subsequently reset. The exit status is true unless a <I>name</I> is readonly. -<DT><B>wait</B> [<B>-n</B>] [<I>n ...</I>]<DD> +<DT><B>wait</B> [<B>-fn</B>] [<I>id ...</I>]<DD> Wait for each specified child process and return its termination status. Each -<I>n</I> +<I>id</I> may be a process ID or a job specification; if a job spec is given, all processes in that job's pipeline are waited for. If -<I>n</I> +<I>id</I> is not given, all currently active child processes are waited for, and the return status is zero. If the <B>-n</B> option is supplied, <B>wait</B> waits for any job to terminate and returns its exit status. +If the <B>-f</B> option is supplied, and job control is enabled, +<B>wait</B> forces <I>id</I> to terminate before returning its status, +instead of returning when it changes status. If -<I>n</I> +<I>id</I> specifies a non-existent process or job, the return status is 127. Otherwise, the return status is the exit status of the last @@ -13529,7 +13852,7 @@ There may be only one active coprocess at a time. <HR> <TABLE WIDTH=100%> <TR> -<TH ALIGN=LEFT width=33%>GNU Bash 4.4<TH ALIGN=CENTER width=33%>2016 August 26<TH ALIGN=RIGHT width=33%>BASH(1) +<TH ALIGN=LEFT width=33%>GNU Bash 5.0<TH ALIGN=CENTER width=33%>2018 March 15<TH ALIGN=RIGHT width=33%>BASH(1) </TR> </TABLE> <HR> @@ -13635,6 +13958,6 @@ There may be only one active coprocess at a time. </DL> <HR> This document was created by man2html from bash.1.<BR> -Time: 31 August 2016 10:24:30 EDT +Time: 19 March 2018 09:43:32 EDT </BODY> </HTML> |