YAP(1)

NAME
yap, more - yet another pager

SYNOPSIS
yap [-cnuq] [-n] [+command] [file ...]

DESCRIPTION
Yap is a program allowing the user to examine a continuous text one screenful at a time on a video display terminal. It does so by pausing after each screenful, waiting for the user to type a command. The commands are enumerated later. Yap's main feature is, that it can page both forwards and backwards, even when reading from standard input.

The command line options are:

-n  An integer which is the size (in lines) of a page (the initial page-size.

-c  Normally, yap will display each page by beginning at the top of the screen and erasing each line just before it displays on it. If your terminal cannot erase a line, yap will clear the screen before it displays a page.
    This avoids scrolling the screen, making it easier to read while yap is writing. The -c option causes yap to scroll the screen instead of beginning at the top of the screen. This is also done if your terminal cannot either erase a line or clear the screen.

-u  Normally, yap handles underlining such as produced by nroff in a manner appropriate to the particular terminal: if the terminal can perform underlining well (t.i., the escape sequences for underlining do not occupy space on the screen), yap will underline underlined information in the input. The -u option supresses this underlining.

-n  Normally, yap also recognises escape sequences for stand-out mode or underlining mode in the input, and knows how much space these escape sequences will occupy on the screen, so that yap will not fold lines erroneously. The -n option supresses this pattern matching.

-q  This option will cause yap to exit only on the "quit" command.

+command
    command is taken to be an initial command to yap.

Yap looks in the YAP environment variable to pre-set flags. For instance, if you prefer the -c mode of operation, just set the YAP environment variable to -c.

The commands of yap can be bound to sequences of keystrokes. The environment variable YAPKEYS may contain the bindings in the form of a list of colon-separated `name=sequence' pairs. The name is a short mnemonic for the command, the sequence is the sequence of keystrokes to be typed to invoke the command. This sequence may contain a ^X escape, which means control-X, and a \X escape, which means X. The latter can be used to get the characters `^', `\' and `:' in the sequence. There are two keymaps available, the default one and a user-defined one. You can switch between one and the other with the change keymap command.

The yap commands are described below. The mnemonics for the commands are given in parentheses. The default key sequences (if any) are given after the mnemonic. Every command takes an optional integer argument, which may be typed before the command. Some commands just ignore it. The integer argument is referred to as i. Usually, if i is not given, it defaults to 1. Visit the i-th previous file given in the command line. If i is not given, scroll one line up. Otherwise, i will be interpreted as a line number. A page starting with the line indicated will then be displayed. Go to the last line of the input. Display the previous page, consisting of i lines, (or page-size lines if no argument is given). Display the previous page, consisting of i lines, (or page-size lines if no argument is given). If i is given, the page-size is set to i. Scroll up i lines (or scroll-size lines if i is not given. Initially, the scroll-size is 11). Search backwards for the i-th occurrence of a regular expression which will be prompted for. If there are less than i occurrences of the expression, the position in the file remains unchanged. Otherwise, a page is displayed, starting two lines before the place where the expression was found. The user's erase and kill characters may be used to edit the expression. Erasing back past the first character cancels the search command.
Note: Some systems do not have regex(3). On those systems, searches are still supported, but regular expressions are not. Skip i lines backwards and display a page. Skip i pages backwards and display a page. Scroll up i lines (or scroll-size lines if i is not given. If i is given, the scroll-size is set to i. Change from the current key map to the other (if there is one). Set the mark to the current page, and display the previously marked page. Visit the i-th next file given in the command line. If i is not given, scroll one line down. Otherwise, i will be interpreted as a line number. A page starting with the line indicated will then be displayed. Display the next page, consisting of i lines, (or page-size lines if no argument is given). Display the next page, consisting of i lines, (or page-size lines if no argument is given). If i is given, the page-size is set to i. Scroll down i lines (or scroll-size lines if no argument is given). Search forwards for the i-th occurrence of a regular expression which will be prompted for. If there are less than i occurrences of the expression, the position in the file remains unchanged. Otherwise, a page is displayed, starting two lines before the place where the expression was found. The user's erase and kill characters may be used to edit the expression. Erasing back past the first character cancels the search command.
Note: Some systems do not have regex(3). On those systems, searches are still supported, but regular expressions are not. Skip i lines and display a page. Skip i pages and display a page. Scroll down i lines (or scroll-size lines if i is not given. If i is given, the scroll-size is set to i. Give a short description of all commands that are bound to a key sequence. Set a mark on the current page. Search for the i-th occurrence of the last regular expression entered, in the direction of the last search. Search for the i-th occurrence of the last regular expression entered, but in the other direction. Exit from yap. Redraw the current page. Repeat the last command. This does not always make sense, so not all commands can be repeated. Invoke the shell with a command that will be prompted for. In the command, the characters `%' and `!' are replaced with the current file name and the previous shell command respectively. The sequences `\%' and `\!' are replaced by `%' and `!' respectively. The user's erase and kill characters can be used to edit the command. Erasing back past the first character cancels the command. Pipe the current input file into a shell command that will be prompted for. The comments given in the description of the shell escape command apply here too. Display the marked page. Display a page starting with the first line of the input. Visit a new file. The filename will be prompted for. If you just type a return, the current file is revisited. Write the input to a file, whose name will be prompted for.

The commands take effect immediately, i.e., it is not necessary to type a carriage return. Up to the time when the command sequence itself is given, the user may give an interrupt to cancel the command being formed.

AUTHOR
Ceriel J.H. Jacobs

SEE ALSO
regex(3).

BUGS
Yap will find your terminal very stupid and act like it, if it has no way of placing the cursor on the home position, or cannot either erase a line or insert one.

In lines longer than about 2000 characters, a linefeed is silently inserted.

The percentage, given in the prompt when yap reads from a file (and knows it), is not always very accurate.