Originální popis anglicky:
more - display files on a page-by-page basis
Návod, kniha: POSIX Programmer's Manual
more [-ceisu][-n
number][-p command][-t
tagstring ][file ...]
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
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.
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.
The standard input shall be used only if no
file operands are specified,
or if a
file operand is
'-' .
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.
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.
Default.
The standard output shall be used to write the contents of the input files.
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.
None.
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.
- Synopsis:
-
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.
- 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.
- 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.
- 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.
- Synopsis:
-
Scroll backward
count lines. The entire
count lines shall be
written, even if
count is more than the screen size.
- 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.
- Synopsis:
-
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.
- 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.
- Synopsis:
-
Display the screenful beginning with line
count.
- Synopsis:
-
If
count is specified, display the screenful beginning with the line
count. Otherwise, display the last screenful of the file.
- Synopsis:
-
Refresh the screen.
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
Return to the position that was previously marked with the letter named by
letter, making that line the current 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.
- 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.
- 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.
- Synopsis:
-
Repeat the previous search for
countth line containing the last
pattern (or not containing the last
pattern, if the previous
search was
"/!" or
"?!" ).
- Synopsis:
-
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
"?!" ).
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
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.
- Synopsis:
-
Exit
more.
The following exit values shall be returned:
- 0
- Successful completion.
- >0
- An error occurred.
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.
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.
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
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.
None.
Shell Command Language ,
ctags ,
ed ,
ex ,
vi
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
.
