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PROGRAM:

NAME

more — display files on a page-by-page basis

SYNOPSIS

more [−ceisu] [−n number] [−p command] [−t tagstring] [file...]

DESCRIPTION

The more utility shall read files and either write them to the terminal on a page-by-page
basis or filter them to standard output. If standard output is not a terminal device, all
input files shall be copied to standard output in their entirety, without modification,
except as specified for the −s option. If standard output is a terminal device, the files
shall be written a number of lines (one screenful) at a time under the control of user
commands. See the EXTENDED DESCRIPTION section.

Certain block-mode terminals do not have all the capabilities necessary to support the
complete more definition; they are incapable of accepting commands that are not terminated
with a <newline>. Implementations that support such terminals shall provide an operating
mode to more in which all commands can be terminated with a <newline> on those terminals.
This mode:

* Shall be documented in the system documentation

* Shall, at invocation, inform the user of the terminal deficiency that requires the
<newline> usage and provide instructions on how this warning can be suppressed in
future invocations

* Shall not be required for implementations supporting only fully capable terminals

* Shall not affect commands already requiring <newline> characters

* Shall not affect users on the capable terminals from using more as described in this
volume of POSIX.1‐2008

OPTIONS

The more utility shall conform to the Base Definitions volume of POSIX.1‐2008, Section
12.2, Utility Syntax Guidelines, except that '+' may be recognized as an option delimiter
as well as '−'.

The following options shall be supported:

−c If a screen is to be written that has no lines in common with the current
screen, or more is writing its first screen, more shall not scroll the screen,
but instead shall redraw each line of the screen in turn, from the top of the
screen to the bottom. In addition, if more is writing its first screen, the
screen shall be cleared. This option may be silently ignored on devices with
insufficient terminal capabilities.

−e Exit immediately after writing the last line of the last file in the argument
list; see the EXTENDED DESCRIPTION section.

−i Perform pattern matching in searches without regard to case; see the Base
Definitions volume of POSIX.1‐2008, Section 9.2, Regular Expression General
Requirements.

−n number Specify the number of lines per screenful. The number argument is a positive
decimal integer. The −n option shall override any values obtained from any other
source.

−p command
Each time a screen from a new file is displayed or redisplayed (including as a
result of more commands; for example, :p), execute the more command(s) in the
command arguments in the order specified, as if entered by the user after the
first screen has been displayed. No intermediate results shall be displayed
(that is, if the command is a movement to a screen different from the normal
first screen, only the screen resulting from the command shall be displayed.) If
any of the commands fail for any reason, an informational message to this effect
shall be written, and no further commands specified using the −p option shall be
executed for this file.

−s Behave as if consecutive empty lines were a single empty line.

−t tagstring
Write the screenful of the file containing the tag named by the tagstring
argument. See the ctags utility. The tags feature represented by −t tagstring
and the :t command is optional. It shall be provided on any system that also
provides a conforming implementation of ctags; otherwise, the use of −t produces
undefined results.

The filename resulting from the −t option shall be logically added as a prefix
to the list of command line files, as if specified by the user. If the tag named
by the tagstring argument is not found, it shall be an error, and more shall
take no further action.

If the tag specifies a line number, the first line of the display shall contain
the beginning of that line. If the tag specifies a pattern, the first line of
the display shall contain the beginning of the matching text from the first line
of the file that contains that pattern. If the line does not exist in the file
or matching text is not found, an informational message to this effect shall be
displayed, and more shall display the default screen as if −t had not been
specified.

If both the −t tagstring and −p command options are given, the −t tagstring
shall be processed first; that is, the file and starting line for the display
shall be as specified by −t, and then the −p more command shall be executed. If
the line (matching text) specified by the −t command does not exist (is not
found), no −p more command shall be executed for this file at any time.

−u Treat a <backspace> as a printable control character, displayed as an
implementation-defined character sequence (see the EXTENDED DESCRIPTION
section), suppressing backspacing and the special handling that produces
underlined or standout mode text on some terminal types. Also, do not ignore a
<carriage-return> at the end of a line.

OPERANDS

The following operand shall be supported:

file A pathname of an input file. If no file operands are specified, the standard
input shall be used. If a file is '−', the standard input shall be read at that
point in the sequence.

STDIN

The standard input shall be used only if no file operands are specified, or if a file
operand is '−'.

INPUT FILES

The input files being examined shall be text files. If standard output is a terminal,
standard error shall be used to read commands from the user. If standard output is a
terminal, standard error is not readable, and command input is needed, more may attempt to
obtain user commands from the controlling terminal (for example, /dev/tty); otherwise,
more shall terminate with an error indicating that it was unable to read user commands. If
standard output is not a terminal, no error shall result if standard error cannot be
opened for reading.

ENVIRONMENT VARIABLES

The following environment variables shall affect the execution of more:

COLUMNS Override the system-selected horizontal display line size. See the Base
Definitions volume of POSIX.1‐2008, Chapter 8, Environment Variables for valid
values and results when it is unset or null.

EDITOR Used by the v command to select an editor. See the EXTENDED DESCRIPTION section.

LANG Provide a default value for the internationalization variables that are unset or
null. (See the Base Definitions volume of POSIX.1‐2008, Section 8.2,
Internationalization Variables for the precedence of internationalization
variables used to determine the values of locale categories.)

LC_ALL If set to a non-empty string value, override the values of all the other
internationalization variables.

LC_COLLATE
Determine the locale for the behavior of ranges, equivalence classes, and multi-
character collating elements within regular expressions.

LC_CTYPE Determine the locale for the interpretation of sequences of bytes of text data
as characters (for example, single-byte as opposed to multi-byte characters in
arguments and input files) and the behavior of character classes within regular
expressions.

LC_MESSAGES
Determine the locale that should be used to affect the format and contents of
diagnostic messages written to standard error and informative messages written
to standard output.

NLSPATH Determine the location of message catalogs for the processing of LC_MESSAGES.

LINES Override the system-selected vertical screen size, used as the number of lines
in a screenful. See the Base Definitions volume of POSIX.1‐2008, Chapter 8,
Environment Variables for valid values and results when it is unset or null. The
−n option shall take precedence over the LINES variable for determining the
number of lines in a screenful.

MORE Determine a string containing options described in the OPTIONS section preceded
with <hyphen> characters and <blank>-separated as on the command line. Any
command line options shall be processed after those in the MORE variable, as if
the command line were:

more $MORE options operands

The MORE variable shall take precedence over the TERM and LINES variables for
determining the number of lines in a screenful.

TERM Determine the name of the terminal type. If this variable is unset or null, an
unspecified default terminal type is used.

ASYNCHRONOUS EVENTS

Default.

STDOUT

The standard output shall be used to write the contents of the input files.

STDERR

The standard error shall be used for diagnostic messages and user commands (see the INPUT
FILES section), and, if standard output is a terminal device, to write a prompting string.
The prompting string shall appear on the screen line below the last line of the file
displayed in the current screenful. The prompt shall contain the name of the file
currently being examined and shall contain an end-of-file indication and the name of the
next file, if any, when prompting at the end-of-file. If an error or informational message
is displayed, it is unspecified whether it is contained in the prompt. If it is not
contained in the prompt, it shall be displayed and then the user shall be prompted for a
continuation character, at which point another message or the user prompt may be
displayed. The prompt is otherwise unspecified. It is unspecified whether informational
messages are written for other user commands.

OUTPUT FILES

None.

EXTENDED DESCRIPTION

The following section describes the behavior of more when the standard output is a
terminal device. If the standard output is not a terminal device, no options other than −s
shall have any effect, and all input files shall be copied to standard output otherwise
unmodified, at which time more shall exit without further action.

The number of lines available per screen shall be determined by the −n option, if present,
or by examining values in the environment (see the ENVIRONMENT VARIABLES section). If
neither method yields a number, an unspecified number of lines shall be used.

The maximum number of lines written shall be one less than this number, because the screen
line after the last line written shall be used to write a user prompt and user input. If
the number of lines in the screen is less than two, the results are undefined. It is
unspecified whether user input is permitted to be longer than the remainder of the single
line where the prompt has been written.

The number of columns available per line shall be determined by examining values in the
environment (see the ENVIRONMENT VARIABLES section), with a default value as described in
the Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment Variables.

Lines that are longer than the display shall be folded; the length at which folding occurs
is unspecified, but should be appropriate for the output device. Folding may occur between
glyphs of single characters that take up multiple display columns.

When standard output is a terminal and −u is not specified, more shall treat <backspace>
and <carriage-return> characters specially:

* A character, followed first by a sequence of n <backspace> characters (where n is the
same as the number of column positions that the character occupies), then by n
<underscore> characters ('_'), shall cause that character to be written as underlined
text, if the terminal type supports that. The n <underscore> characters, followed
first by n <backspace> characters, then any character with n column positions, shall
also cause that character to be written as underlined text, if the terminal type
supports that.

* A sequence of n <backspace> characters (where n is the same as the number of column
positions that the previous character occupies) that appears between two identical
printable characters shall cause the first of those two characters to be written as
emboldened text (that is, visually brighter, standout mode, or inverse-video mode), if
the terminal type supports that, and the second to be discarded. Immediately
subsequent occurrences of <backspace>/character pairs for that same character shall
also be discarded. (For example, the sequence "a\ba\ba\ba" is interpreted as a single
emboldened 'a'.)

* The more utility shall logically discard all other <backspace> characters from the
line as well as the character which precedes them, if any.

* A <carriage-return> at the end of a line shall be ignored, rather than being written
as a non-printable character, as described in the next paragraph.

It is implementation-defined how other non-printable characters are written.
Implementations should use the same format that they use for the ex print command; see the
OPTIONS section within the ed utility. It is unspecified whether a multi-column character
shall be separated if it crosses a display line boundary; it shall not be discarded. The
behavior is unspecified if the number of columns on the display is less than the number of
columns any single character in the line being displayed would occupy.

When each new file is displayed (or redisplayed), more shall write the first screen of the
file. Once the initial screen has been written, more shall prompt for a user command. If
the execution of the user command results in a screen that has lines in common with the
current screen, and the device has sufficient terminal capabilities, more shall scroll the
screen; otherwise, it is unspecified whether the screen is scrolled or redrawn.

For all files but the last (including standard input if no file was specified, and for the
last file as well, if the −e option was not specified), when more has written the last
line in the file, more shall prompt for a user command. This prompt shall contain the name
of the next file as well as an indication that more has reached end-of-file. If the user
command is f, <control>‐F, <space>, j, <newline>, d, <control>‐D, or s, more shall display
the next file. Otherwise, if displaying the last file, more shall exit. Otherwise, more
shall execute the user command specified.

Several of the commands described in this section display a previous screen from the input
stream. In the case that text is being taken from a non-rewindable stream, such as a pipe,
it is implementation-defined how much backwards motion is supported. If a command cannot
be executed because of a limitation on backwards motion, an error message to this effect
shall be displayed, the current screen shall not change, and the user shall be prompted
for another command.

If a command cannot be performed because there are insufficient lines to display, more
shall alert the terminal. If a command cannot be performed because there are insufficient
lines to display or a / command fails: if the input is the standard input, the last screen
in the file may be displayed; otherwise, the current file and screen shall not change, and
the user shall be prompted for another command.

The interactive commands in the following sections shall be supported. Some commands can
be preceded by a decimal integer, called count in the following descriptions. If not
specified with the command, count shall default to 1. In the following descriptions,
pattern is a basic regular expression, as described in the Base Definitions volume of
POSIX.1‐2008, Section 9.3, Basic Regular Expressions. The term ``examine'' is historical
usage meaning ``open the file for viewing''; for example, more foo would be expressed as
examining file foo.

In the following descriptions, unless otherwise specified, line is a line in the more
display, not a line from the file being examined.

In the following descriptions, the current position refers to two things:

1. The position of the current line on the screen

2. The line number (in the file) of the current line on the screen

Usually, the line on the screen corresponding to the current position is the third line on
the screen. If this is not possible (there are fewer than three lines to display or this
is the first page of the file, or it is the last page of the file), then the current
position is either the first or last line on the screen as described later.

Help
Synopsis:
h

Write a summary of these commands and other implementation-defined commands. The behavior
shall be as if the more utility were executed with the −e option on a file that contained
the summary information. The user shall be prompted as described earlier in this section
when end-of-file is reached. If the user command is one of those specified to continue to
the next file, more shall return to the file and screen state from which the h command was
executed.

Scroll Forward One Screenful
Synopsis:
[count]f
[count]<control>-F

Scroll forward count lines, with a default of one screenful. If count is more than the
screen size, only the final screenful shall be written.

Scroll Backward One Screenful
Synopsis:
[count]b
[count]<control>-B

Scroll backward count lines, with a default of one screenful (see the −n option). If count
is more than the screen size, only the final screenful shall be written.

Scroll Forward One Line
Synopsis:
[count]<space>
[count]j
[count]<newline>

Scroll forward count lines. The default count for the <space> shall be one screenful; for
j and <newline>, one line. The entire count lines shall be written, even if count is more
than the screen size.

Scroll Backward One Line
Synopsis:
[count]k

Scroll backward count lines. The entire count lines shall be written, even if count is
more than the screen size.

Scroll Forward One Half Screenful
Synopsis:
[count]d
[count]<control>-D

Scroll forward count lines, with a default of one half of the screen size. If count is
specified, it shall become the new default for subsequent d, <control>‐D, and u commands.

Skip Forward One Line
Synopsis:
[count]s

Display the screenful beginning with the line count lines after the last line on the
current screen. If count would cause the current position to be such that less than one
screenful would be written, the last screenful in the file shall be written.

Scroll Backward One Half Screenful
Synopsis:
[count]u
[count]<control>-U

Scroll backward count lines, with a default of one half of the screen size. If count is
specified, it shall become the new default for subsequent d, <control>−D, u, and
<control>−U commands. The entire count lines shall be written, even if count is more than
the screen size.

Go to Beginning of File
Synopsis:
[count]g

Display the screenful beginning with line count.

Go to End-of-File
Synopsis:
[count]G

If count is specified, display the screenful beginning with the line count. Otherwise,
display the last screenful of the file.

Refresh the Screen
Synopsis:
r
<control>-L

Refresh the screen.

Discard and Refresh
Synopsis:
R

Refresh the screen, discarding any buffered input. If the current file is non-seekable,
buffered input shall not be discarded and the R command shall be equivalent to the r
command.

Mark Position
Synopsis:
mletter

Mark the current position with the letter named by letter, where letter represents the
name of one of the lowercase letters of the portable character set. When a new file is
examined, all marks may be lost.

Return to Mark
Synopsis:
'letter

Return to the position that was previously marked with the letter named by letter, making
that line the current position.

Return to Previous Position
Synopsis:
''

Return to the position from which the last large movement command was executed (where a
``large movement'' is defined as any movement of more than a screenful of lines). If no
such movements have been made, return to the beginning of the file.

Search Forward for Pattern
Synopsis:
[count]/[!]pattern<newline>

Display the screenful beginning with the countth line containing the pattern. The search
shall start after the first line currently displayed. The null regular expression ('/'
followed by a <newline>) shall repeat the search using the previous regular expression,
with a default count. If the character '!' is included, the matching lines shall be
those that do not contain the pattern. If no match is found for the pattern, a message to
that effect shall be displayed.

Search Backward for Pattern
Synopsis:
[count]?[!]pattern<newline>

Display the screenful beginning with the countth previous line containing the pattern. The
search shall start on the last line before the first line currently displayed. The null
regular expression ('?' followed by a <newline>) shall repeat the search using the
previous regular expression, with a default count. If the character '!' is included,
matching lines shall be those that do not contain the pattern. If no match is found for
the pattern, a message to that effect shall be displayed.

Repeat Search
Synopsis:
[count]n

Repeat the previous search for countth line containing the last pattern (or not containing
the last pattern, if the previous search was "/!" or "?!").

Repeat Search in Reverse
Synopsis:
[count]N

Repeat the search in the opposite direction of the previous search for the countth line
containing the last pattern (or not containing the last pattern, if the previous search
was "/!" or "?!").

Examine New File
Synopsis:
:e [filename]<newline>

Examine a new file. If the filename argument is not specified, the current file (see the
:n and :p commands below) shall be re-examined. The filename shall be subjected to the
process of shell word expansions (see Section 2.6, Word Expansions); if more than a single
pathname results, the effects are unspecified. If filename is a <number-sign> ('#'), the
previously examined file shall be re-examined. If filename is not accessible for any
reason (including that it is a non-seekable file), an error message to this effect shall
be displayed and the current file and screen shall not change.

Examine Next File
Synopsis:
[count]:n

Examine the next file. If a number count is specified, the countth next file shall be
examined. If filename refers to a non-seekable file, the results are unspecified.

Examine Previous File
Synopsis:
[count]:p

Examine the previous file. If a number count is specified, the countth previous file shall
be examined. If filename refers to a non-seekable file, the results are unspecified.

Go to Tag
Synopsis:
:t tagstring<newline>

If the file containing the tag named by the tagstring argument is not the current file,
examine the file, as if the :e command was executed with that file as the argument.
Otherwise, or in addition, display the screenful beginning with the tag, as described for
the −t option (see the OPTIONS section). If the ctags utility is not supported by the
system, the use of :t produces undefined results.

Invoke Editor
Synopsis:
v

Invoke an editor to edit the current file being examined. If standard input is being
examined, the results are unspecified. The name of the editor shall be taken from the
environment variable EDITOR, or shall default to vi. If the last pathname component in
EDITOR is either vi or ex, the editor shall be invoked with a −c linenumber command line
argument, where linenumber is the line number of the file line containing the display line
currently displayed as the first line of the screen. It is implementation-defined whether
line-setting options are passed to editors other than vi and ex.

When the editor exits, more shall resume with the same file and screen as when the editor
was invoked.

Display Position
Synopsis:
=
<control>-G

Write a message for which the information references the first byte of the line after the
last line of the file on the screen. This message shall include the name of the file
currently being examined, its number relative to the total number of files there are to
examine, the line number in the file, the byte number and the total bytes in the file, and
what percentage of the file precedes the current position. If more is reading from
standard input, or the file is shorter than a single screen, the line number, the byte
number, the total bytes, and the percentage need not be written.

Quit
Synopsis:
q
:q
ZZ

Exit more.

EXIT STATUS

The following exit values shall be returned:

0 Successful completion.

>0 An error occurred.

CONSEQUENCES OF ERRORS

If an error is encountered accessing a file when using the :n command, more shall attempt
to examine the next file in the argument list, but the final exit status shall be
affected. If an error is encountered accessing a file via the :p command, more shall
attempt to examine the previous file in the argument list, but the final exit status shall
be affected. If an error is encountered accessing a file via the :e command, more shall
remain in the current file and the final exit status shall not be affected.

The following sections are informative.

APPLICATION USAGE

When the standard output is not a terminal, only the −s filter-modification option is
effective. This is based on historical practice. For example, a typical implementation of
man pipes its output through more −s to squeeze excess white space for terminal users.
When man is piped to lp, however, it is undesirable for this squeezing to happen.

EXAMPLES

The −p allows arbitrary commands to be executed at the start of each file. Examples are:

more −p G file1 file2
Examine each file starting with its last screenful.

more −p 100 file1 file2
Examine each file starting with line 100 in the current position (usually the third
line, so line 98 would be the first line written).

more −p /100 file1 file2
Examine each file starting with the first line containing the string "100" in the
current position

RATIONALE

The more utility, available in BSD and BSD-derived systems, was chosen as the prototype
for the POSIX file display program since it is more widely available than either the
public-domain program less or than pg, a pager provided in System V. The 4.4 BSD more is
the model for the features selected; it is almost fully upwards-compatible from the 4.3
BSD version in wide use and has become more amenable for vi users. Several features
originally derived from various file editors, found in both less and pg, have been added
to this volume of POSIX.1‐2008 as they have proved extremely popular with users.

There are inconsistencies between more and vi that result from historical practice. For
example, the single-character commands h, f, b, and <space> are screen movers in more, but
cursor movers in vi. These inconsistencies were maintained because the cursor movements
are not applicable to more and the powerful functionality achieved without the use of the
control key justifies the differences.

The tags interface has been included in a program that is not a text editor because it
promotes another degree of consistent operation with vi. It is conceivable that the
paging environment of more would be superior for browsing source code files in some
circumstances.

The operating mode referred to for block-mode terminals effectively adds a <newline> to
each Synopsis line that currently has none. So, for example, d<newline> would page one
screenful. The mode could be triggered by a command line option, environment variable, or
some other method. The details are not imposed by this volume of POSIX.1‐2008 because
there are so few systems known to support such terminals. Nevertheless, it was considered
that all systems should be able to support more given the exception cited for this small
community of terminals because, in comparison to vi, the cursor movements are few and the
command set relatively amenable to the optional <newline> characters.

Some versions of more provide a shell escaping mechanism similar to the ex ! command. The
standard developers did not consider that this was necessary in a paginator, particularly
given the wide acceptance of multiple window terminals and job control features. (They
chose to retain such features in the editors and mailx because the shell interaction also
gives an opportunity to modify the editing buffer, which is not applicable to more.)

The −p (position) option replaces the + command because of the Utility Syntax Guidelines.
The +command option is no longer specified by POSIX.1‐2008 but may be present in some
implementations. In early proposals, it took a pattern argument, but historical less
provided the more general facility of a command. It would have been desirable to use the
same −c as ex and vi, but the letter was already in use.

The text stating ``from a non-rewindable stream ... implementations may limit the amount
of backwards motion supported'' would allow an implementation that permitted no backwards
motion beyond text already on the screen. It was not possible to require a minimum amount
of backwards motion that would be effective for all conceivable device types. The
implementation should allow the user to back up as far as possible, within device and
reasonable memory allocation constraints.

Historically, non-printable characters were displayed using the ARPA standard mappings,
which are as follows:

1. Printable characters are left alone.

2. Control characters less than \177 are represented as followed by the character offset
from the '@' character in the ASCII map; for example, \007 is represented as 'G'.

3. \177 is represented as followed by '?'.

The display of characters having their eighth bit set was less standard. Existing
implementations use hex (0x00), octal (\000), and a meta-bit display. (The latter
displayed characters with their eighth bit set as the two characters "M−", followed by the
seven-bit display as described previously.) The latter probably has the best claim to
historical practice because it was used with the −v option of 4 BSD and 4 BSD-derived
versions of the cat utility since 1980.

No specific display format is required by POSIX.1‐2008. Implementations are encouraged to
conform to historic practice in the absence of any strong reason to diverge.

FUTURE DIRECTIONS

None.

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