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| -rw-r--r-- | Base/usr/share/man/man5/Shell.md | 39 |
1 files changed, 38 insertions, 1 deletions
diff --git a/Base/usr/share/man/man5/Shell.md b/Base/usr/share/man/man5/Shell.md index 77f84300da..1fd7a72a58 100644 --- a/Base/usr/share/man/man5/Shell.md +++ b/Base/usr/share/man/man5/Shell.md @@ -28,6 +28,10 @@ String of characters that are not _Special_ or _Syntactic Elements_ ##### Glob String of characters containing at least one of `*?` in _bareword_ position +##### History Events +A _designator_ starting with `!` in _bareword_ position that describes a word or a range of words from a previously entered command. +Please look at the section named 'History Event Designators' for a more thorough explanation. Only allowed in interactive mode. + ##### Single Quoted String Any sequence of characters between two single quotes (`'`) @@ -36,6 +40,7 @@ Any sequence of _Double Quoted String Part_ tokens: * Barewords * Single Quotes * Variable References +* History Events * Evaluate expressions * Escaped sequences @@ -309,6 +314,25 @@ match "$(make_some_value)" { } ``` +### History Event Designators +History expansion may be utilised to reuse previously typed words or commands. +Such expressions are of the general form `!<event_designator>(:<word_designator>)`, where `event_designator` would select an entry in the shell history, and `word_designator` would select a word (or a range of words) from that entry. + +| Event designator | effect | +| :- | :----- | +| `!` | Select the immediately preceding command | +| _n_ | Select the _n_'th entry in the history | +| -_n_ | Select the last _n_'th entry in the history | +| _str_ | Select the most recent entry starting with _str_ | +| ?_str_ | Select the most recent entry containing _str_ | + +| Word designator | effect | +| :-- | :----- | +| _n_ | The _n_'th word, starting with 0 as the command | +| `^` | The first word (index 0) | +| `$` | The last word | +| _x_-_y_ | The range of words starting at _x_ and ending at _y_ (inclusive) | + ## Formal Grammar ### Shell Grammar @@ -382,6 +406,7 @@ list_expression :: ' '* expression (' '+ list_expression)? expression :: evaluate expression? | string_composite expression? | comment expression? + | history_designator expression? | '(' list_expression ')' expression? evaluate :: '$' '(' pipe_sequence ')' @@ -391,7 +416,7 @@ string_composite :: string string_composite? | variable string_composite? | bareword string_composite? | glob string_composite? - | brace string_composite? + | brace_expansion string_composite? string :: '"' dquoted_string_inner '"' | "'" [^']* "'" @@ -411,6 +436,18 @@ variable :: '$' identifier comment :: '#' [^\n]* +history_designator :: '!' event_selector (':' word_selector_composite)? + +event_selector :: '!' {== '-0'} + | '?' bareword '?' + | bareword {number: index, otherwise: lookup} + +word_selector_composite :: word_selector ('-' word_selector)? + +word_selector :: number + | '^' {== 0} + | '$' {== end} + bareword :: [^"'*$&#|()[\]{} ?;<>] bareword? | '\' [^"'*$&#|()[\]{} ?;<>] bareword? |