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Annotation of 43BSD/contrib/mh/miscellany/less/less.l, revision 1.1

1.1     ! root        1: .TH LESS l
        !             2: .SH NAME
        !             3: less \- opposite of more
        !             4: .SH SYNOPSIS
        !             5: .B "less [-cdepstwmMqQuU] [-h\fIn\fB] [-b[fp]\fIn\fB] [-x\fIn\fB] [+\fIcmd\fB] [\fIname\fB] ..."
        !             6: .SH DESCRIPTION
        !             7: .I Less
        !             8: is a program similar to 
        !             9: .I more
        !            10: (1), but which allows backwards movement
        !            11: in the file as well as forward movement.
        !            12: Also,
        !            13: .I less
        !            14: does not have to read the entire input file before starting,
        !            15: so with large input files it starts up faster than text editors like
        !            16: .I vi
        !            17: (1).
        !            18: .I Less
        !            19: uses termcap, so it can run on a variety of terminals.
        !            20: There is even limited support for hardcopy terminals.
        !            21: (On a hardcopy terminal, lines which should be printed at the top
        !            22: of the screen are prefixed with an up-arrow.)
        !            23: .PP
        !            24: Commands are based on both
        !            25: .I more
        !            26: and
        !            27: .I vi.
        !            28: Commands may be preceeded by a decimal number, 
        !            29: called N in the descriptions below.
        !            30: The number is used by some commands, as indicated.
        !            31: 
        !            32: .SH COMMANDS
        !            33: .IP h
        !            34: Help: display a summary of these commands.
        !            35: If you forget all the other commands, remember this one.
        !            36: .PP
        !            37: .IP SPACE
        !            38: Scroll forward N lines, default one screen.
        !            39: If N is more than the screen size, only one screenful is displayed.
        !            40: .PP
        !            41: .IP f
        !            42: Same as SPACE.
        !            43: .PP
        !            44: .IP b
        !            45: Scroll backward N lines, default one screen.
        !            46: If N is more than the screen size, only one screenful is displayed.
        !            47: .PP
        !            48: .IP RETURN
        !            49: Scroll forward N lines, default 1.
        !            50: If N is more than the screen size, the entire N lines are displayed.
        !            51: .PP
        !            52: .IP e
        !            53: Same as RETURN.
        !            54: .PP
        !            55: .IP j
        !            56: Also the same as RETURN.
        !            57: .PP
        !            58: .IP y
        !            59: Scroll backward N lines, default 1.
        !            60: If N is more than the screen size, the entire N lines are displayed.
        !            61: .IP k
        !            62: Same as y.
        !            63: .PP
        !            64: .IP d
        !            65: Scroll forward N lines, default 10.
        !            66: If N is specified, it becomes the new default for all d and u commands.
        !            67: .PP
        !            68: .IP u
        !            69: Scroll backward N lines, default 10.
        !            70: If N is specified, it becomes the new default for all d and u commands.
        !            71: .PP
        !            72: .IP r
        !            73: Repaint the screen.
        !            74: .PP
        !            75: .IP R
        !            76: Repaint the screen, discarding any buffered input.
        !            77: Useful if the file is changing while it is being viewed.
        !            78: .PP
        !            79: .IP g
        !            80: Go to line N in the file, default 1 (beginning of file).
        !            81: (Warning: this may be slow if N is large.)
        !            82: .PP
        !            83: .IP G
        !            84: Go to line N in the file, default the end of the file.
        !            85: (Warning: this may be slow if standard input, 
        !            86: rather than a file, is being read.)
        !            87: .PP
        !            88: .IP p
        !            89: Go to a position N percent into the file.
        !            90: N should be between 0 and 100.
        !            91: (This is possible if standard input is being read,
        !            92: but only if
        !            93: .I less
        !            94: has already read to the end of the file.
        !            95: It is always fast, but not always useful.)
        !            96: .PP
        !            97: .IP %
        !            98: Same as p.
        !            99: .PP
        !           100: .IP m
        !           101: Followed by any lowercase letter, marks the current position with that letter.
        !           102: .PP
        !           103: .IP "'"
        !           104: Followed by any lowercase letter, returns to the position which
        !           105: was previously marked with that letter.
        !           106: All marks are lost when a new file is examined.
        !           107: .PP
        !           108: .IP /pattern
        !           109: Search forward in the file for the N-th occurence of the pattern.
        !           110: N defaults to 1.
        !           111: The pattern is a regular expression, as recognized by
        !           112: .I ed.
        !           113: The search starts at the second line displayed
        !           114: (but see the -t option, which changes this).
        !           115: .PP
        !           116: .IP ?pattern
        !           117: Search backward in the file for the N-th occurence of the pattern.
        !           118: The search starts at the line immediately before the top line displayed.
        !           119: .PP
        !           120: .IP n
        !           121: Repeat previous search, for N-th occurence of the last pattern.
        !           122: .PP
        !           123: .IP E [filename]
        !           124: Examine a new file.
        !           125: If the filename is missing, the "current" file (see the N and P commands
        !           126: below) from the list of files in the command line is re-examined.
        !           127: .PP
        !           128: .IP N
        !           129: Examine the next file (from the list of files given in the command line).
        !           130: If a number N is specified (not to be confused with the command N),
        !           131: the N-th next file is examined.
        !           132: .PP
        !           133: .IP P
        !           134: Examine the previous file.
        !           135: If a number N is specified, the N-th previous file is examined.
        !           136: .PP
        !           137: .IP =
        !           138: Prints the name of the file being viewed
        !           139: and the byte offset of the bottom line being displayed.
        !           140: If possible, it also prints the length of the file
        !           141: and the percent of the file above the last displayed line.
        !           142: .PP
        !           143: .IP \-
        !           144: Followed by one of the command line option letters (see below),
        !           145: this will toggle the setting of that option
        !           146: and print a message describing the new setting.
        !           147: .PP
        !           148: .IP V
        !           149: Prints the version number of 
        !           150: .I less 
        !           151: being run.
        !           152: .PP
        !           153: .IP q
        !           154: Exits
        !           155: .I less.
        !           156: .PP
        !           157: The following 
        !           158: two 
        !           159: commands may or may not be valid, depending on your particular installation.
        !           160: .PP
        !           161: .IP v
        !           162: Invokes an editor to edit the current file being viewed.
        !           163: The editor is taken from the environment variable EDITOR,
        !           164: or defaults to "vi".
        !           165: .PP
        !           166: .IP "! shell-command"
        !           167: Invokes a shell to run the shell-command given.
        !           168: .PP
        !           169: .SH OPTIONS
        !           170: Command line options are described below.
        !           171: Options are also taken from the environment variable "LESS".
        !           172: (The environment variable is parsed before the command line,
        !           173: so command line options override the LESS environment variable.
        !           174: Options may be changed while
        !           175: .I less 
        !           176: is running via the "\-" command.)
        !           177: For example, if you like 
        !           178: more-style prompting, to avoid typing "less -m ..." each time 
        !           179: .I less 
        !           180: is invoked, you might tell 
        !           181: .I csh:
        !           182: .sp
        !           183: setenv LESS m
        !           184: .sp
        !           185: or if you use 
        !           186: .I sh:
        !           187: .sp
        !           188: LESS=m; export LESS
        !           189: .IP -s
        !           190: The -s flag causes
        !           191: consecutive blank lines to be squeezed into a single blank line.
        !           192: This is useful when viewing
        !           193: .I nroff
        !           194: output.
        !           195: .IP -t
        !           196: Normally, forward searches start just after
        !           197: the top displayed line (that is, at the second displayed line).
        !           198: Thus forward searches include the currently displayed screen.
        !           199: The -t command line option causes forward searches to start 
        !           200: just after the bottom line displayed,
        !           201: thus skipping the currently displayed screen.
        !           202: .IP -m
        !           203: Normally,
        !           204: .I less
        !           205: prompts with a colon.
        !           206: The -m command line option causes 
        !           207: .I less
        !           208: to prompt verbosely like 
        !           209: .I more,
        !           210: printing the file name and percent into the file.
        !           211: .IP -M
        !           212: The -M command line option causes 
        !           213: .I less
        !           214: to prompt even more verbosely than 
        !           215: .I more.
        !           216: .IP -q
        !           217: Normally, if an attempt is made to scroll past the end of the file
        !           218: or before the beginning of the file, the terminal bell is rung to
        !           219: indicate this fact.
        !           220: The -q command line option tells
        !           221: .I less
        !           222: not to ring the bell at such times.
        !           223: If the terminal has a "visual bell", it is used instead.
        !           224: .IP -Q
        !           225: Even if -q is given, 
        !           226: .I less 
        !           227: will ring the bell on certain other errors,
        !           228: such as typing an invalid character.
        !           229: The -Q command line option tells
        !           230: .I less
        !           231: to be quiet all the time; that is, never ring the terminal bell.
        !           232: If the terminal has a "visual bell", it is used instead.
        !           233: .IP -e
        !           234: Normally the only way to exit less is via the "q" command.
        !           235: The -e command line option tells less to automatically exit
        !           236: the second time it reaches end-of-file.
        !           237: .IP -u
        !           238: If the -u command line option is given, 
        !           239: backspaces are treated as printable characters;
        !           240: that is, they are sent to the terminal when they appear in the input.
        !           241: .IP -U
        !           242: If the -U command line option is given,
        !           243: backspaces are printed as the two character sequence "^H".
        !           244: If neither -u nor -U is given,
        !           245: backspaces which appear adjacent to an underscore character
        !           246: are treated specially:
        !           247: the underlined text is displayed 
        !           248: using the terminal's hardware underlining capability.
        !           249: .IP -w
        !           250: Normally,
        !           251: .I less
        !           252: uses a tilde character to represent lines past the end of the file.
        !           253: The -w option causes blank lines to be used instead.
        !           254: .IP -d
        !           255: Normally,
        !           256: .I less
        !           257: will complain if the terminal is dumb; that is, lacks some important capability,
        !           258: such as the ability to clear the screen or scroll backwards.
        !           259: The -d flag suppresses this complaint 
        !           260: (but does not otherwise change the behavior of the program on a dumb terminal).
        !           261: .IP -p
        !           262: Normally, 
        !           263: .I less 
        !           264: will repaint the screen by scrolling from the bottom of the screen.
        !           265: If the -p flag is set, when
        !           266: .I less 
        !           267: needs to change the entire display, it will clear the screen
        !           268: and paint from the top line down.
        !           269: .IP -h
        !           270: Normally,
        !           271: .I less
        !           272: will scroll backwards when backwards movement is necessary.
        !           273: The -h option specifies a maximum number of lines to scroll backwards.
        !           274: If it is necessary to move backwards more than this many lines,
        !           275: the screen is repainted in a forward direction.
        !           276: (If the terminal does not have the ability to scroll
        !           277: backwards, -h0 is implied.)
        !           278: .IP -x
        !           279: The -x\fIn\fR command line option sets tab stops every \fIn\fR positions.
        !           280: The default for \fIn\fR is 8.
        !           281: .IP -b
        !           282: The -b\fIn\fR command line option tells
        !           283: .I less
        !           284: to use a non-standard buffer size.
        !           285: There are two standard (default) buffer sizes,
        !           286: one is used when a file is being read and the other
        !           287: when a pipe (standard input) is being read.
        !           288: The current defaults are 5 buffers for files and 12 for pipes.
        !           289: (Buffers are 1024 bytes.)
        !           290: The number \fIn\fR specifies a different number of buffers to use.
        !           291: The -b may be followed by "f", in which case only 
        !           292: the file default is changed, or by "p" in which case only the 
        !           293: pipe default is changed.  Otherwise, both are changed.
        !           294: .IP -c
        !           295: Normally, when data is read by
        !           296: .I less,
        !           297: it is scanned to ensure that bit 7 (the high order bit) is turned off in
        !           298: each byte read, and to ensure that there are no null (zero) bytes in
        !           299: the data (null bytes are turned into "@" characters).
        !           300: If the data is known to be "clean",
        !           301: the -c command line option will tell 
        !           302: .I less
        !           303: to skip this checking, causing an imperceptible speed improvement.
        !           304: (However, if the data is not "clean", unpredicatable results may occur.)
        !           305: .IP +
        !           306: If a command line option begins with \fB+\fR,
        !           307: the remainder of that option is taken to be an initial command to
        !           308: .I less.
        !           309: For example, +G tells
        !           310: .I less
        !           311: to start at the end of the file rather than the beginning,
        !           312: and +/xyz tells it to start at the first occurence of "xyz" in the file.
        !           313: As a special case, +<number> acts like +<number>g; 
        !           314: that is, it starts the display at the specified line number
        !           315: (however, see the caveat under the "g" command above).
        !           316: If the option starts with \fB++\fR, the initial command applies to
        !           317: every file being viewed, not just the first one.
        !           318: 
        !           319: .SH BUGS
        !           320: When used on standard input (rather than a file), you can move
        !           321: backwards only a finite amount, corresponding to that portion
        !           322: of the file which is still buffered.

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