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

       psed - a stream editor

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

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

       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

       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.

       -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

       -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

       sed command syntax is defined as


       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 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.

       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

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

           The line with the given number is selected.

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

       /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

       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.

       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

       [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.

           Deletes the pattern space and starts the next cycle.

           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.

           Replace the contents of the pattern space with the hold space.

           Append a newline and the contents of the hold space to the pattern

           Replace the contents of the hold space with the pattern space.

           Append a newline and the contents of the pattern space to the hold

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

           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.

           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.

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

           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.)

           Prints the pattern space through the first embedded newline or to the

           Branch to the end of the script and quit without starting a new

       [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.

           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

           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.

           Swap the contents of the pattern space and the hold space.

           In the pattern space, replace all characters occurring 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.

           Prints the current line number on the standard output.

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

       [2addr]{ [command]
           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

       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.

       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.

       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

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

   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

       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

       To enable this feature, the environment variable PSEDEXTBRE must be set
       to a string containing the requested characters, e.g.:

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

       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 substitution 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

       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

       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

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

          #no autoprint
          s/^.*Warn( *"\([^"]*\)".*$/\1/
          t process
          s/^/=item /

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

       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.

       perl(1), re_format(7)

       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.

       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").

       This Perl implementation of sed was written by Wolfgang Laun,

       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.

perl v5.18.4                       2021-11-13                             S2P(1)