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>s
* Shall not affect users on the capable terminals from using more as
described in this volume of IEEE Std 1003.1-2001
OPTIONS
The more utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
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 By default, more shall exit immediately after writing the last
line of the last file in the argument list. If the -e option is
specified:
1. If there is only a single file in the argument list and that
file was completely displayed on a single screen, more shall
exit immediately after writing the last line of that file.
2. Otherwise, more shall exit only after reaching end-of-file
on the last file in the argument list twice without an
intervening operation. See the EXTENDED DESCRIPTION section.
-i Perform pattern matching in searches without regard to case; see
the Base Definitions volume of IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001, 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
IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001, 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 hyphens 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 IEEE Std 1003.1-2001, 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>s and <carriage-return>s specially:
* A character, followed first by a sequence of n <backspace>s (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>s, 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>s (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>s 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
IEEE Std 1003.1-2001, 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 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
IEEE Std 1003.1-2001 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
IEEE Std 1003.1-2001 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>s.
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. 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 IEEE Std 1003.1-2001.
Implementations are encouraged to conform to historic practice in the
absence of any strong reason to diverge.
FUTURE DIRECTIONS
None.
SEE ALSO
Shell Command Language , ctags , ed , ex , vi
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .