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80 lines
2.6 KiB
Markdown
80 lines
2.6 KiB
Markdown
## Name
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`less` - A full-featured terminal pager.
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## Synopsis
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```**sh
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$ cat file | less [-PXNem]
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$ less [-PXNem] [file]
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$ cat file | more
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$ more [file]
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```
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## Description
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`less` is a terminal pager that allows backwards movement. It is inspired by,
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but largely incompatible with
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[GNU less](https://www.greenwoodsoftware.com/less/index.html).
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## Options
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* `-P`, `--prompt`: Set the prompt format string. See [Prompts](#prompts) for more details.
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* `-X`, `--no-init`: Don't switch to the xterm alternate buffer on startup.
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* `-N`, `--line-numbers`: Show line numbers before printed lines.
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* `-e`, `--quit-at-eof`: Immediately exit less when the last line of the document is reached.
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* `-m`, `--emulate-more`: Apply `-Xe`, set the prompt to `--More--`, and disable
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scrollback. This option is automatically applied when `less` is executed as `more`
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## Commands
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Commands may be preceded by a decimal number `N`. Currently, this feature
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does not exist, and no command use `N`.
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| Command | Description |
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|---------|-------------|
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| `q` | Exit less. |
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| `j` or `DOWNARROW` or `ENTER` | Go to the next line. |
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| `k` or `UPARROW` | Go to the previous line. |
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| `f` or `SPACE` | Go to the next page. |
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| `b` | Go to the previous page. |
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## Prompts
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`less` accepts a special prompt string with the `-P` option. prompts accept a
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variety of format specifiers so that they adapt to `less`'s state.
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A `%` followed by a letter will be replaced with the associated variable. If
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such a variable does not exist, or currently has no value, it will be replaced
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with a `?`.
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| Variable | Description |
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|----------|-------------|
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| `%f` | Replaced with the name of the current file |
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| `%l` | Replaced with the current line number |
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A `?` followed by a letter acts as an if expression on the associated
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condition. `:` then acts as the else, and `.` acts as the end token. for example
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if you wanted to print 'true' if you are at the end of the file and 'false'
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otherwise, your prompt would be `?etrue:false.`. These expressions are
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arbitrarily nestable. If a condition does not exist, then it will always
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evaluate it's false branch.
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| Condition | Description |
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|----------|-------------|
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| `?f` | True when reading from a file other than stdin. |
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| `?e` | True when at the end of a file. |
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A `\\` followed by any character will be replaced with the literal value of the
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character. For instance, `\\%l` would render as `%l`.
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All other characters are treated normally.
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#### Examples
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`less`'s current default prompt: `'?f%f :.(line %l)?e (END):.'`
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## See Also
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* [`more`(1)](help://man/1/more) For a simpler pager that less implements.
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* [`man`(1)](help://man/1/man) For serenity's manual pager, that uses less.
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