


S2P(1)           Perl Programmers Reference Guide          S2P(1)


NAME
       psed - a stream editor

SYNOPSIS
          psed [-an] script [file ...]
          psed [-an] [-e script] [-f script-file] [file ...]

          s2p  [-an] [-e script] [-f script-file]

DESCRIPTION
       A stream editor reads the input stream consisting of the
       specified files (or standard input, if none are given),
       processes is line by line by applying a script consisting
       of edit commands, and writes resulting lines to standard
       output. The filename `"-"' may be used to read standard
       input.

       The edit script is composed from arguments of -e options
       and script-files, in the given order. A single script
       argument may be specified as the first parameter.

       If this program is invoked with the name s2p, it will act
       as a sed-to-Perl translator. See "sed Script Translation".

       sed returns an exit code of 0 on success or >0 if an error
       occurred.

OPTIONS
       -a  A file specified as argument to the w edit command is
           by default opened before input processing starts.
           Using -a, opening of such files is delayed until the
           first line is actually written to the file.

       -e script
           The editing commands defined by script are appended to
           the script.  Multiple commands must be separated by
           newlines.

       -f script-file
           Editing commands from the specified script-file are
           read and appended to the script.

       -n  By default, a line is written to standard output after
           the editing script has been applied to it. The -n
           option suppresses automatic printing.

COMMANDS
       sed command syntax is defined as

          [address[,address]][!]function[argument]

       with whitespace being permitted before or after addresses,
       and between the function character and the argument. The
       addresses and the address inverter ("!") are used to



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       restrict the application of a command to the selected
       line(s) of input.

       Each command must be on a line of its own, except where
       noted in the synopses below.

       The edit cycle performed on each input line consist of
       reading the line (without its trailing newline character)
       into the pattern space, applying the applicable commands
       of the edit script, writing the final contents of the
       pattern space and a newline to the standard output.  A
       hold space is provided for saving the contents of the
       pattern space for later use.

   Addresses
       A sed address is either a line number or a pattern, which
       may be combined arbitrarily to construct ranges. Lines are
       numbered across all input files.

       Any address may be followed by an exclamation mark
       (`"!"'), selecting all lines not matching that address.

       number
           The line with the given number is selected.

       $   A dollar sign ("$") is the line number of the last
           line of the input stream.

       /regular expression/
           A pattern address is a basic regular expression (see
           "Basic Regular Expressions"), between the delimiting
           character "/".  Any other character except "\" or
           newline may be used to delimit a pattern address when
           the initial delimiter is prefixed with a backslash
           (`"\"').

       If no address is given, the command selects every line.

       If one address is given, it selects the line (or lines)
       matching the address.

       Two addresses select a range that begins whenever the
       first address matches, and ends (including that line) when
       the second address matches.  If the first (second) address
       is a matching pattern, the second address is not applied
       to the very same line to determine the end of the range.
       Likewise, if the second address is a matching pattern, the
       first address is not applied to the very same line to
       determine the begin of another range. If both addresses
       are line numbers, and the second line number is less than
       the first line number, then only the first line is
       selected.





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   Functions
       The maximum permitted number of addresses is indicated
       with each function synopsis below.

       The argument text consists of one or more lines following
       the command.  Embedded newlines in text must be preceded
       with a backslash.  Other backslashes in text are deleted
       and the following character is taken literally.

       [1addr]a\ text
           Write text (which must start on the line following the
           command) to standard output immediately before reading
           the next line of input, either by executing the N
           function or by beginning a new cycle.

       [2addr]b [label]
           Branch to the : function with the specified label. If
           no label is given, branch to the end of the script.

       [2addr]c\ text
           The line, or range of lines, selected by the address
           is deleted.  The text (which must start on the line
           following the command) is written to standard output.
           With an address range, this occurs at the end of the
           range.

       [2addr]d
           Deletes the pattern space and starts the next cycle.

       [2addr]D
           Deletes the pattern space through the first embedded
           newline or to the end.  If the pattern space becomes
           empty, a new cycle is started, otherwise execution of
           the script is restarted.

       [2addr]g
           Replace the contents of the pattern space with the
           hold space.

       [2addr]G
           Append a newline and the contents of the hold space to
           the pattern space.

       [2addr]h
           Replace the contents of the hold space with the
           pattern space.

       [2addr]H
           Append a newline and the contents of the pattern space
           to the hold space.

       [1addr]i\ text
           Write the text (which must start on the line following
           the command) to standard output.



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       [2addr]l
           Print the contents of the pattern space: non-printable
           characters are shown in C-style escaped form; long
           lines are split and have a trailing `"\"' at the point
           of the split; the true end of a line is marked with a
           `"$"'. Escapes are: `\a', `\t', `\n', `\f', `\r', `\e'
           for BEL, HT, LF, FF, CR, ESC, respectively, and `\'
           followed by a three-digit octal number for all other
           non-printable characters.

       [2addr]n
           If automatic printing is enabled, write the pattern
           space to the standard output. Replace the pattern
           space with the next line of input. If there is no more
           input, processing is terminated.

       [2addr]N
           Append a newline and the next line of input to the
           pattern space. If there is no more input, processing
           is terminated.

       [2addr]p
           Print the pattern space to the standard output. (Use
           the -n option to suppress automatic printing at the
           end of a cycle if you want to avoid double printing of
           lines.)

       [2addr]P
           Prints the pattern space through the first embedded
           newline or to the end.

       [1addr]q
           Branch to the end of the script and quit without
           starting a new cycle.

       [1addr]r file
           Copy the contents of the file to standard output
           immediately before the next attempt to read a line of
           input. Any error encountered while reading file is
           silently ignored.

       [2addr]s/regular expression/replacement/flags
           Substitute the replacement string for the first
           substring in the pattern space that matches the
           regular expression.  Any character other than
           backslash or newline can be used instead of a slash to
           delimit the regular expression and the replacement.
           To use the delimiter as a literal character within the
           regular expression and the replacement, precede the
           character by a backslash (`"\"').

           Literal newlines may be embedded in the replacement
           string by preceding a newline with a backslash.




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           Within the replacement, an ampersand (`"&"') is
           replaced by the string matching the regular
           expression. The strings `"\1"' through `"\9"' are
           replaced by the corresponding subpattern (see "Basic
           Regular Expressions").  To get a literal `"&"' or
           `"\"' in the replacement text, precede it by a
           backslash.

           The following flags modify the behaviour of the s
           command:

           g       The replacement is performed for all matching,
                   non-overlapping substrings of the pattern
                   space.

           1..9    Replace only the n-th matching substring of
                   the pattern space.

           p       If the substitution was made, print the new
                   value of the pattern space.

           w file  If the substitution was made, write the new
                   value of the pattern space to the specified
                   file.

       [2addr]t [label]
           Branch to the : function with the specified label if
           any s substitutions have been made since the most
           recent reading of an input line or execution of a t
           function. If no label is given, branch to the end of
           the script.

       [2addr]w file
           The contents of the pattern space are written to the
           file.

       [2addr]x
           Swap the contents of the pattern space and the hold
           space.

       [2addr]y/string1/string2/
           In the pattern space, replace all characters occuring
           in string1 by the character at the corresponding
           position in string2. It is possible to use any
           character (other than a backslash or newline) instead
           of a slash to delimit the strings.  Within string1 and
           string2, a backslash followed by any character other
           than a newline is that literal character, and a
           backslash followed by an `n' is replaced by a newline
           character.

       [1addr]=
           Prints the current line number on the standard output.




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       [0addr]: [label]
           The command specifies the position of the label. It
           has no other effect.

       [2addr]{ [command]
       [0addr]}
           These two commands begin and end a command list. The
           first command may be given on the same line as the
           opening { command. The commands within the list are
           jointly selected by the address(es) given on the {
           command (but may still have individual addresses).

       [0addr]# [comment]
           The entire line is ignored (treated as a comment). If,
           however, the first two characters in the script are
           `"#n"', automatic printing of output is suppressed, as
           if the -n option were given on the command line.

BASIC REGULAR EXPRESSIONS
       A Basic Regular Expression (BRE), as defined in POSIX
       1003.2, consists of atoms, for matching parts of a string,
       and bounds, specifying repetitions of a preceding atom.

   Atoms
       The possible atoms of a BRE are: ., matching any single
       character; ^ and $, matching the null string at the
       beginning or end of a string, respectively; a bracket
       expressions, enclosed in [ and ] (see below); and any
       single character with no other significance (matching that
       character). A \ before one of: ., ^, $, [, *, \, matching
       the character after the backslash. A sequence of atoms
       enclosed in \( and \) becomes an atom and establishes the
       target for a backreference, consisting of the substring
       that actually matches the enclosed atoms.  Finally, \
       followed by one of the digits 0 through 9 is a
       backreference.

       A ^ that is not first, or a $ that is not last does not
       have a special significance and need not be preceded by a
       backslash to become literal. The same is true for a ],
       that does not terminate a bracket expression.

       An unescaped backslash cannot be last in a BRE.

   Bounds
       The BRE bounds are: *, specifying 0 or more matches of the
       preceding atom; \{count\}, specifying that many
       repetitions; \{minimum,\}, giving a lower limit; and
       \{minimum,maximum\} finally defines a lower and upper
       bound.

       A bound appearing as the first item in a BRE is taken
       literally.




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   Bracket Expressions
       A bracket expression is a list of characters, character
       ranges and character classes enclosed in [ and ] and
       matches any single character from the represented set of
       characters.

       A character range is written as two characters separated
       by - and represents all characters (according to the
       character collating sequence) that are not less than the
       first and not greater than the second.  (Ranges are very
       collating-sequence-dependent, and portable programs should
       avoid relying on them.)

       A character class is one of the class names

          alnum     digit     punct
          alpha     graph     space
          blank     lower     upper
          cntrl     print     xdigit

       enclosed in [: and :] and represents the set of characters
       as defined in ctype(3).

       If the first character after [ is ^, the sense of matching
       is inverted.

       To include a literal `"^"', place it anywhere else but
       first. To include a literal '"]"' place it first or
       immediately after an initial ^. To include a literal `"-"'
       make it the first (or second after ^) or last character,
       or the second endpoint of a range.

       The special bracket expression constructs "[[:<:]]" and
       "[[:>:]]" match the null string at the beginning and end
       of a word respectively.  (Note that neither is identical
       to Perl's `\b' atom.)

   Additional Atoms
       Since some sed implementations provide additional regular
       expression atoms (not defined in POSIX 1003.2), psed is
       capable of translating the following backslash escapes:

       \< This is the same as "[[:>:]]".
       \> This is the same as "[[:<:]]".
       \w This is an abbreviation for "[[:alnum:]_]".
       \W This is an abbreviation for "[^[:alnum:]_]".
       \y Match the empty string at a word boundary.
       \B Match the empty string between any two either word or
       non-word characters.

       To enable this feature, the environment variable
       PSEDEXTBRE must be set to a string containing the
       requested characters, e.g.: "PSEDEXTBRE='<>wW'".




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ENVIRONMENT
       The environment variable "PSEDEXTBRE" may be set to extend
       BREs.  See "Additional Atoms".

DIAGNOSTICS
       ambiguous translation for character `%s' in `y' command
           The indicated character appears twice, with different
           translations.

       `[' cannot be last in pattern
           A `[' in a BRE indicates the beginning of a bracket
           expression.

       `\' cannot be last in pattern
           A `\' in a BRE is used to make the subsequent
           character literal.

       `\' cannot be last in substitution
           A `\' in a subsitution string is used to make the
           subsequent character literal.

       conflicting flags `%s'
           In an s command, either the `g' flag and an n-th
           occurrence flag, or multiple n-th occurrence flags are
           specified. Note that only the digits `1' through `9'
           are permitted.

       duplicate label %s (first defined at %s)
       excess address(es)
           The command has more than the permitted number of
           addresses.

       extra characters after command (%s)
       illegal option `%s'
       improper delimiter in s command
           The BRE and substitution may not be delimited with `\'
           or newline.

       invalid address after `,'
       invalid backreference (%s)
           The specified backreference number exceeds the number
           of backreferences in the BRE.

       invalid repeat clause `\{%s\}'
           The repeat clause does not contain a valid integer
           value, or pair of values.

       malformed regex, 1st address
       malformed regex, 2nd address
       malformed regular expression
       malformed substitution expression
       malformed `y' command argument
           The first or second string of a y command  is
           syntactically incorrect.



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       maximum less than minimum in `\{%s\}'
       no script command given
           There must be at least one -e or one -f option
           specifying a script or script file.

       `\' not valid as delimiter in `y' command
       option -e requires an argument
       option -f requires an argument
       `s' command requires argument
       start of unterminated `{'
       string lengths in `y' command differ
           The translation table strings in a y command must have
           equal lengths.

       undefined label `%s'
       unexpected `}'
           A } command without a preceding { command was
           encountered.

       unexpected end of script
           The end of the script was reached although a text line
           after a a, c or i command indicated another line.

       unknown command `%s'
       unterminated `['
           A BRE contains an unterminated bracket expression.

       unterminated `\('
           A BRE contains an unterminated backreference.

       `\{' without closing `\}'
           A BRE contains an unterminated bounds specification.

       `\)' without preceding `\('
       `y' command requires argument

EXAMPLE
       The basic material for the preceding section was generated
       by running the sed script

          #no autoprint
          s/^.*Warn( *"\([^"]*\)".*$/\1/
          t process
          b
          :process
          s/$!/%s/g
          s/$[_[:alnum:]]\{1,\}/%s/g
          s/\\\\/\\/g
          s/^/=item /
          p

       on the program's own text, and piping the output into
       "sort -u".




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SED SCRIPT TRANSLATION
       If this program is invoked with the name s2p it will act
       as a sed-to-Perl translator. After option processing (all
       other arguments are ignored), a Perl program is printed on
       standard output, which will process the input stream (as
       read from all arguments) in the way defined by the sed
       script and the option setting used for the translation.

SEE ALSO
       perl(1), re_format(7)

BUGS
       The l command will show escape characters (ESC) as `"\e"',
       but a vertical tab (VT) in octal.

       Trailing spaces are truncated from labels in :, t and b
       commands.

       The meaning of an empty regular expression (`"//"'), as
       defined by sed, is "the last pattern used, at run time".
       This deviates from the Perl interpretation, which will re-
       use the "last last successfully executed regular
       expression". Since keeping track of pattern usage would
       create terribly cluttered code, and differences would only
       appear in obscure context (where other sed implementations
       appear to deviate, too), the Perl semantics was adopted.
       Note that common usage of this feature, such as in
       "/abc/s//xyz/", will work as expected.

       Collating elements (of bracket expressions in BREs) are
       not implemented.

STANDARDS
       This sed implementation conforms to the IEEE
       Std1003.2-1992 ("POSIX.2") definition of sed, and is
       compatible with the OpenBSD implementation, except where
       otherwise noted (see "BUGS").

AUTHOR
       This Perl implementation of sed was written by Wolfgang
       Laun, Wolfgang.Laun@alcatel.at.

COPYRIGHT and LICENSE
       This program is free and open software. You may use,
       modify, distribute, and sell this program (and any
       modified variants) in any way you wish, provided you do
       not restrict others from doing the same.










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