pg - file perusal filter for CRTs
pg [ -number ] [ -p string ] [ -cefnrs ] [ +linenumber ] [ +/pattern<b>/ ] [
file . . . ]
The pg command is a filter that allows the examination of files one
screenful at a time on a CRT. (If no file is specified or if it
encounters the file name -, pg reads from standard input.) Each
screenful is followed by a prompt. If the user types a carriage return,
another page is displayed; other possibilities are listed below. pg
processes supplementary code set characters in files, and recognizes
supplementary code set characters in the string given to the -p option
(see below) according to the locale specified in the LC_CTYPE environment
variable [see LANG on environ(5)]. In regular expressions, pattern
searches are performed on characters, not bytes, as described on ed(1).
This command is different from previous paginators in that it allows you
to back up and review something that has already passed. The method for
doing this is explained below.
To determine terminal attributes, pg scans the terminfo(4) data base for
the terminal type specified by the environment variable TERM. If TERM is
not defined, the terminal type dumb is assumed.
The command line options are:
An integer specifying the size (in lines) of the window that pg is
to use instead of the default. (On a terminal containing 24 lines,
the default window size is 23).
-c Home the cursor and clear the screen before displaying each page.
This option is ignored if clear_screen is not defined for this
terminal type in the terminfo(4) data base.
-e Causes pg not to pause at the end of each file.
-f Normally, pg splits lines longer than the screen width at
characters, but some sequences of characters in the text being
displayed (for example, escape sequences for underlining) generate
undesirable results. The -f option inhibits pg from splitting
-n Normally, commands must be terminated by a newline character. This
option causes an automatic end of command as soon as a command
letter is entered.
Causes pg to use string as the prompt. If the prompt string
contains a %d, the first occurrence of %d' in the prompt will be
replaced by the current page number when the prompt is issued. The
default prompt string is ``:''. string may contain supplementary
code set characters.
-r Restricted mode. The shell escape is disallowed. pg will print an
error message but does not exit.
-s Causes pg to print all messages and prompts in standout mode
(usually inverse video).
Start up at linenumber.
Start up at the first line containing the regular expression
The responses that may be typed when pg pauses can be divided into three
categories: those causing further perusal, those that search, and those
that modify the perusal environment.
Commands that cause further perusal normally take a preceding address, an
optionally signed number indicating the point from which further text
should be displayed. This address is interpreted in either pages or
lines depending on the command. A signed address specifies a point
relative to the current page or line, and an unsigned address specifies
an address relative to the beginning of the file. Each command has a
default address that is used if none is provided.
The perusal commands and their defaults are as follows:
(+1)<newline> or <blank>
This causes one page to be displayed. The address is specified in
With a relative address this causes pg to simulate scrolling the
screen, forward or backward, the number of lines specified. With an
absolute address this command prints a screenful beginning at the
(+1) d or ^D
Simulates scrolling half a screen forward or backward.
i<b>f Skip i screens of text.
i<b>z Same as newline except that i, if present, becomes the new default
number of lines per screenful.
The following perusal commands take no address.
. or ^L
Typing a single period causes the current page of text to be
$ Displays the last windowful in the file. Use with caution when the
input is a pipe.
The following commands are available for searching for text patterns in
the text. The regular expressions described in ed(1) are available.
They must always be terminated by a newline, even if the -n option is
Search forward for the ith (default i=1) occurrence of pattern.
Searching begins immediately after the current page and continues to
the end of the current file, without wrap-around.
Search backwards for the ith (default i=1) occurrence of pattern.
Searching begins immediately before the current page and continues
to the beginning of the current file, without wrap-around. The ^
notation is useful for Adds 100 terminals which will not properly
handle the ?.
After searching, pg will normally display the line found at the top of
the screen. This can be modified by appending m or b to the search
command to leave the line found in the middle or at the bottom of the
window from now on. The suffix t can be used to restore the original
The user of pg can modify the environment of perusal with the following
i<b>n Begin perusing the ith next file in the command line. The i is an
unsigned number, default value is 1.
i<b>p Begin perusing the ith previous file in the command line. i is an
unsigned number, default is 1.
i<b>w Display another window of text. If i is present, set the window
size to i.
Save the input in the named file. Only the current file being
perused is saved. The white space between the s and filename is
optional. This command must always be terminated by a newline, even
if the -n option is specified.
h Help by displaying an abbreviated summary of available commands.
q or Q
Command is passed to the shell, whose name is taken from the SHELL
environment variable. If this is not available, the default shell
is used. This command must always be terminated by a newline, even
if the -n option is specified.
At any time when output is being sent to the terminal, the user can hit
the quit key (normally CTRL-\) or the interrupt (break) key. This causes
pg to stop sending output, and display the prompt. The user may then
enter one of the above commands in the normal manner. Unfortunately,
some output is lost when this is done, because any characters waiting in
the terminal's output queue are flushed when the quit signal occurs.
If the standard output is not a terminal, then pg acts just like cat(1),
except that a header is printed before each file (if there is more than
The following command line uses pg to read the system news:
news | pg -p "(Page %d):"
terminal information database
temporary file when input is from a pipe
language-specific message file [See LANG on environ (5).]
ed(1), grep(1), terminfo(4)
While waiting for terminal input, pg responds to BREAK, DEL, and CTRL-\
by terminating execution. Between prompts, however, these signals
interrupt pg's current task and place the user in prompt mode. These
should be used with caution when input is being read from a pipe, since
an interrupt is likely to terminate the other commands in the pipeline.
The terminal /, ^, or ? may be omitted from the searching commands.
If terminal tabs are not set every eight positions, undesirable results
When using pg as a filter with another command that changes the terminal
I/O options, terminal settings may not be restored correctly.
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