In this tutorial on Linux pg, 54 of 100, below find a 3-4 minute introductory video, a text-based tutorial and all of the code examples from the video.
Our fifty-fourth word, or command to memorize is
pg from our category
Text.
pg allows you to view text files
page-by-page.
Common Linux pg Options
-options
description
--help
Print help screen
-c
Clear screen before each page
-NUMBER
Set the NUMBER of lines on a page
Recall from back in video 5, on less,
that was my preferred pager, and I mentioned Linux includes a variety of
pagers and pg is one of them. In the
next few videos, to be fair, I want to introduce you to other text
programs.
Before we start, it helps to think of commands as mini programs and
most follow this structure:
command -option(s) argument(s).
The pg command has
12 options and the argument is the text file to view,
and because pg is a separate program
it has its own internal commands, and there are about
15 of those.
Like most commands, help is available with double-dash
--help. The
-c option clears the screen before
each page, and since pages sometimes don't fit on the screen, use
dash and a number to change this.
So why is pg an important command?
Well, you'll work with text often in Linux and functionality is highly
personal so it's up to you to find your preferred pager.
And now you know how to do that.
Demonstration
Okay, the best way to embed this in your memory is by typing in your
own terminal window.
Find this on your Mac using a program called Terminal. On Linux use
Terminal or Konsole, and currently Microsoft is adding this
functionality to Windows.
Here we go. Let's pull the manual page on
pg and redirect it
> to a text file called
video54.txt so we have something to
work with.
$ man pg > video54.txt
$ _
Next type pg and that file name
video54.txt.
PG(1) User Commands PG(1)
NAME
pg - browse pagewise through text files
SYNOPSIS
pg [-amount] [-p prompt] [-cefnrs] [+line] [+/pattern/] [file...]
DESCRIPTION
pg displays a text file on a CRT one screenful at once. After each page, a prompt is displayed.
The user may then either press the newline key to view the next page or one of the keys described
below.
If no filename is given on the command line, pg reads from standard input. If standard output is
not a terminal, pg acts like cat(1) but precedes each file with its name if there is more than one.
If input comes from a pipe, pg stores the data in a buffer file while reading, to make navigation
possible.
OPTIONS
pg accepts the following options:
+number
Start at the given line number.
+/pattern/
Start at the line containing the Basic Regular Expression pattern given.
:_
And then, to page to the next page, hit
Enter.
Start at the line containing the Basic Regular Expression pattern given.
-number
The number of lines per page. By default, this is the number of CRT lines minus one.
-c Clear the screen before a page is displayed, if the terminfo entry for the terminal provides
this capability.
-e Do not pause and display (EOF) at the end of a file.
-f Do not split long lines.
-n Without this option, commands must be terminated by a newline character. With this option,
pg advances once a command letter is entered.
-p string
Instead of the normal prompt :, string is displayed. If string contains %d, its first occurrence is replaced by the number of the current page.
-r Disallow the shell escape.
-s Print messages in standout mode, if the terminfo entry for the terminal provides this
capability.
-V, --version
Disaplay version information and exit.
-h, --help
Display help text and exit.
:_
Enter
Display help text and exit.
COMMANDS
The following commands may be entered at the prompt. Commands preceded by i in this document
accept a number as argument, positive or negative. If this argument starts with + or -, it is
interpreted relative to the current position in the input file, otherwise relative to the begin-
ning.
i<Enter>
Display the next or the indicated page.
id or ^D
Display the next halfpage. If i is given, it is always interpreted relative to the current
position.
il Display the next or the indicated line.
if Skip a page forward. i must be a positive number and is always interpreted relative to the current
position.
iw or iz
As <Enter> except that i becomes the new page size.
. or ^L
Redraw the screen.
$ Advance to the last line of the input file.
i/pattern/
:_
And then notice how it's hard to know when it all ends?
i/pattern/
Search forward until the first or the i-th occurrence of the Basic Regular Expression pat-
tern is found. The search starts after the current page and stops at the end of the file.
No wrap-around is performed. i must be a positive number.
i?pattern? or i^pattern^
Search backward until the first or the i-th occurrence of the Basic Regular Expression pat-
tern is found. The search starts before the current page and stops at the beginning of the
file. No wrap-around is performed. i must be a positive number.
The search commands accept an added letter. If t is given, the line containing the
pattern is dis-
played at the top of the screen, which is the default. m selects the middle and b the bottom of
the screen. The selected position is used in following searches, too.
in Advance to the next file or i files forward.
ip Reread the previous file or i files backward.
s filename
Save the current file to the given filename.
h Display a command summary.
!command
Execute command using the shell.
q or Q Quit.
If the user presses the interrupt or quit key while pg reads from the input file or or writes on the
:_
Let's work on that.
If the user presses the interrupt or quit key whil pg reads from the input file or writes on the
terminal, pg will immediately display the prompt. In all other situations these keys will termi-
nate pg.
ENVIRONMENT VARIABLES
The following environment variables affect the behavior of pg:
COLUMNS
Overrides the system-supplied number of columns if set.
LANG, LC_ALL, LC_COLLATE, LC_CTYPE, LC_MESSAGES
See locale(7).
LINES Overrides the system-supplied number of lines if set.
SHELL Used by the ! command.
TERM Determines the terminal type.
SEE ALSO
cat(1), more(1), sh(1), terminfo(5), locale(7), regex(7), term(7)
NOTES
pg expects the terminal tabulators to be set every eight positions.
Files that include NUL characters cannot be displayed by pg.
AVAILABILITY
The pg command is part of the util-linux package and is available from ftp://ftp.ker-
nel.org/pub/linux/utils/util-linux/.
util-linux July 2014 PG(1)
(EOF):_
(hit qto return to the command prompt)
So, with the options -c and
-20, for lines per page.
$ pg -c -20 video54.txt
This improves viewing.
PG(1) User Commands PG(1)
NAME
pg - browse pagewise through text files
SYNOPSIS
pg [-amount] [-p prompt] [-cefnrs] [+line] [+/pattern/] [file...]
DESCRIPTION
pg displays a text file on a CRT one screenful at once. After each page, a prompt is displayed.
The user may then either press the newline key to view the next page or one of the keys described
below.
If no filename is given on the command line, pg reads from standard input. If stan dard output is not
a terminal, pg acts like cat(1) but precedes each file with its name if there is more than one.
If input comes from a pipe, pg stores the data in a buffer file while reading, to make navigation
possible.
:_
And I'll page through here (Enter)
so you can see what I'm talking about.
possible.
OPTIONS
pg accepts the following options:
+number
Start at the given line number.
+/pattern/
Start at the line containing the Basic Regular Expression pattern given.
-number
The number of lines per page. By default, this is the number of CRT lines minus one.
-c Clear the screen before a page is displayed, if the terminfo entry for the terminal provides
this capability.
-e Do not pause and display (EOF) at the end of a file.
-f Do not split long lines.
:_
Hit q Enter to go back to the
command prompt.
And last, a command within
pg.
$ pg -c -20 video54.txt
One of those internal commands I mentioned.
PG(1) User Commands PG(1)
NAME
pg - browse pagewise through text files
SYNOPSIS
pg [-amount] [-p prompt] [-cefnrs] [+line] [+/pattern/] [file...]
DESCRIPTION
pg displays a text file on a CRT one screenful at once. After each page, a prompt is displayed.
The user may then either press the newline key to view the next page or one of the keys described
below.
If no filename is given on the command line, pg reads from standard input. If standard output is
not a terminal, pg acts like cat(1) but precedes each file with its name if there is more than one.
If input comes from a pipe, pg stores the data in a buffer file while reading, to make navigation
possible.
:_
Type i and notice how the prompt changes,
then enter 3 Enter for page 3.
-n Without this option, commands must be terminated by a newline character. With this option,
pg advances once a command letter is entered.
-p string
Instead of the normal prompt :, string is displayed. If string contains %d, its first
occurrence is replaced by the number of the current page.
-r Disallow the shell escape.
-s Print messages in standout mode, if the terminfo entry for the terminal provides this capa-
bility.
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.
COMMANDS
:_
Again, type q Enter to leave.
A Final Tip
Okay now you know how to use pg.
And you know the syntax for commands, options and arguments.
One last tip about the pg command.
So I suggest playing around with
pg and see if you
prefer it over less, and I'll
introduce you to more next.
Okay, thanks for visiting today. I hope this was a helpful
introduction to the pg command.
Learn More About The Series
For an overview of the 100 videos, the 8 quizzes, a cheat sheet, the
categories and a Q&A section, visit:
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