s2p
a stream editor
see also :
perl
Synopsis
psed [-an] script [file ...]
psed [-an] [-e script] [-f script-file] [file ...]
s2p [-an] [-e script] [-f script-file]
add an example, a script, a trick and tips
examples
source
public = a2p
s2p find2perl
private =
manpages = a2p.man
s2p.man
util =
sh = Makefile.SH
cflags.SH
shextract =
Makefile cflags
plextract =
find2perl s2p
plexe =
find2perl.exe s2p.exe
plc = find2perl.c
s2p.c
plm = a2p.loadmap
addedbyconf =
$(shextract)
$(plextract)
source
public = a2p
s2p find2perl
private =
manpages = a2p.man
s2p.man
util =
sh = Makefile.SH
cflags.SH
shextract =
Makefile cflags
plextract =
find2perl s2p
plexe =
find2perl.exe s2p.exe
plc = find2perl.c
s2p.c
plm = a2p.loadmap
addedbyconf =
$(shextract)
$(plextract)
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.
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.
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'".
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 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.
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.
[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.
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 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.
[1addr]=
Prints the current line number on the standard output.
[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.
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.
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 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 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.
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
environment
The environment variable "PSEDEXTBRE" may be set to
extend BREs. See "Additional Atoms".
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".
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.
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 ").
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.
see also
perl ,
re_format
author
This Perl
implementation of sed was written by Wolfgang Laun,
Wolfgang.Laun[:at:]alcatel[:dot:]at.