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Shell: Improve the parsing of history event designators

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TheFightingCatfish 2021-07-30 18:55:57 +08:00 • committed by Ali Mohammad Pur
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Base/usr/share/man/man5/Shell.md
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@ -362,20 +362,25 @@ match "$(make_some_value)" {
History expansion may be utilized to reuse previously typed words or commands.
Such expressions are of the general form `!<event_designator>(:<word_designator>)`, where `event_designator` would select an entry in the shell history, and `word_designator` would select a word (or a range of words) from that entry.
| Event designator | effect |
| Event designator | Effect |
| :- | :----- |
| `!` | Select the immediately preceding command |
| _n_ | Select the _n_'th entry in the history |
| -_n_ | Select the last _n_'th entry in the history |
| _str_ | Select the most recent entry starting with _str_ |
| ?_str_ | Select the most recent entry containing _str_ |
| `!` | The immediately preceding command |
| _n_ | The _n_'th entry in the history, starting with 1 as the first entry |
| -_n_ | The last _n_'th entry in the history, starting with -1 as the previous entry |
| _str_ | The most recent entry starting with _str_ |
| `?`_str_ | The most recent entry containing _str_ |
| Word designator | effect |
| Word designator | Effect |
| :-- | :----- |
| _n_ | The _n_'th word, starting with 0 as the command |
| `^` | The first word (index 0) |
| `$` | The last word |
| _x_-_y_ | The range of words starting at _x_ and ending at _y_ (inclusive) |
| _n_ | The word at index _n_, starting with 0 as the first word (usually the command) |
| `^` | The first argument (index 1) |
| `$` | The last argument |
| _x_-_y_ | The range of words starting at _x_ and ending at _y_ (inclusive). _x_ defaults to 0 if omitted |
| `*` | All the arguments. Equivalent to `^`-`$` |
| _x_`*` | The range of words starting at _x_ and ending at the last word (`$`) (inclusive) |
| _x_- | The range of words starting at _x_ and ending at the second to last word (inclusive). _x_ defaults to 0 if omitted |
Note: The event designator and the word designator should usually be separated by a colon (`:`). This colon can be omitted only if the word designator starts with `^`, `$` or `*` (such as `!1^` for the first argument of the first entry in the history).
## Formal Grammar