PG(1)PG(1)NAMEpg - files perusal filter for CRTs
SYNOPSISpg [-number] [-p string] [-cefnrs] [+ linenumber]
[+/ pattern /] [filename]...
The pg command is a filter that allows the examination of filenames one
screenful at a time on a CRT. If the user types a RETURN, another page
is displayed; other possibilities are listed below.
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.
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).
pg uses string as the prompt. If the prompt string con‐
tains 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 ``:''.
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
pg does not pause at the end of each file.
Normally, pg splits lines longer than the screen width,
but some sequences of characters in the text being dis‐
played (for instance, escape sequences for underlining)
generate undesirable results. The -f option inhibits pg
from splitting lines.
Normally, commands must be terminated by a <newline>
character. This option causes an automatic end of com‐
mand as soon as a command letter is entered.
Restricted mode. The shell escape is disallowed. pg
prints an error message but does not exit.
pg prints all messages and prompts in the standard out‐
put mode (usually inverse video).
Start up at linenumber.
Start up at the first line containing the regular
The following operands are supported:
A path name of a text file to be displayed. If no filename
is given, or if it is −, the standard input is read.
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 pages.
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 speci‐
(+1) d or ^D
Simulates scrolling half a screen forward
Skip i screens of text.
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
Displays the last full window in the file. Use with cau‐
tion when the input is a pipe.
The following commands are available for searching for text patterns in
the text. The regular expressions are described on the regex(5) manual
page. They must always be terminated by a <newline>, even if the -n
option is specified.
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, with‐
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 com‐
mand to leave the line found in the middle or at the bottom of the win‐
dow from now on. The suffix t can be used to restore the original situ‐
The user of pg can modify the environment of perusal with the following
Begin perusing the ith next file in the command line. The
i is an unsigned number, default value is 1.
Begin perusing the ith previous file in the command line.
i is an unsigned number, default is 1.
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 spec‐
Help by displaying an abbreviated summary of available
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 spec‐
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. Unfortu‐
nately, some output is lost when this is done, because any characters
waiting in the terminal's output queue are flushed when the quit signal
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 one).
Large File Behavior
See largefile(5) for the description of the behavior of pg when encoun‐
tering files greater than or equal to 2 Gbyte ( 2^31 bytes).
Example 1 An example of the pg command.
The following command line uses pg to read the system news:
example% news | pg-p "(Page %d):"
See environ(5) for descriptions of the following environment variables
that affect the execution of pg: LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following environment variables affect the execution of pg:
Determine the horizontal screen size. If unset or NULL, use
the value of TERM, the window size, baud rate, or some com‐
bination of these, to indicate the terminal type for the
screen size calculation.
Determine the number of lines to be displayed on the screen.
If unset or NULL, use the value of TERM, the window size,
baud rate, or some combination of these, to indicate the
terminal type for the screen size calculation.
Determine the name of the command interpreter executed for a
Determine terminal attributes. Optionally attempt to search
a system-dependent database, keyed on the value of the TERM
environment variable. If no information is available, a ter‐
minal incapable of cursor-addressable movement is assumed.
The following exit values are returned:
An error occurred.
temporary file when input is from a pipe
terminal information database
SEE ALSOcat(1), grep(1), more(1), terminfo(4), attributes(5), environ(5),
While waiting for terminal input, pg responds to BREAK, CTRL-C, and
CTRL−\ by terminating execution. Between prompts, however, these sig‐
nals 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
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 termi‐
nal I/O options, terminal settings may not be restored correctly.
Feb 25, 1996 PG(1)