/usr.bin/sed/sed.1
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- .\" @(#)sed.1 8.2 (Berkeley) 12/30/93
- .\" $FreeBSD$
- .\"
- .Dd May 24, 2009
- .Dt SED 1
- .Os
- .Sh NAME
- .Nm sed
- .Nd stream editor
- .Sh SYNOPSIS
- .Nm
- .Op Fl Ealnr
- .Ar command
- .Op Ar
- .Nm
- .Op Fl Ealnr
- .Op Fl e Ar command
- .Op Fl f Ar command_file
- .Op Fl I Ar extension
- .Op Fl i Ar extension
- .Op Ar
- .Sh DESCRIPTION
- The
- .Nm
- utility reads the specified files, or the standard input if no files
- are specified, modifying the input as specified by a list of commands.
- The input is then written to the standard output.
- .Pp
- A single command may be specified as the first argument to
- .Nm .
- Multiple commands may be specified by using the
- .Fl e
- or
- .Fl f
- options.
- All commands are applied to the input in the order they are specified
- regardless of their origin.
- .Pp
- The following options are available:
- .Bl -tag -width indent
- .It Fl E
- Interpret regular expressions as extended (modern) regular expressions
- rather than basic regular expressions (BRE's).
- The
- .Xr re_format 7
- manual page fully describes both formats.
- .It Fl a
- The files listed as parameters for the
- .Dq w
- functions are created (or truncated) before any processing begins,
- by default.
- The
- .Fl a
- option causes
- .Nm
- to delay opening each file until a command containing the related
- .Dq w
- function is applied to a line of input.
- .It Fl e Ar command
- Append the editing commands specified by the
- .Ar command
- argument
- to the list of commands.
- .It Fl f Ar command_file
- Append the editing commands found in the file
- .Ar command_file
- to the list of commands.
- The editing commands should each be listed on a separate line.
- .It Fl I Ar extension
- Edit files in-place, saving backups with the specified
- .Ar extension .
- If a zero-length
- .Ar extension
- is given, no backup will be saved.
- It is not recommended to give a zero-length
- .Ar extension
- when in-place editing files, as you risk corruption or partial content
- in situations where disk space is exhausted, etc.
- .Pp
- Note that in-place editing with
- .Fl I
- still takes place in a single continuous line address space covering
- all files, although each file preserves its individuality instead of
- forming one output stream.
- The line counter is never reset between files, address ranges can span
- file boundaries, and the
- .Dq $
- address matches only the last line of the last file.
- (See
- .Sx "Sed Addresses" . )
- That can lead to unexpected results in many cases of in-place editing,
- where using
- .Fl i
- is desired.
- .It Fl i Ar extension
- Edit files in-place similarly to
- .Fl I ,
- but treat each file independently from other files.
- In particular, line numbers in each file start at 1,
- the
- .Dq $
- address matches the last line of the current file,
- and address ranges are limited to the current file.
- (See
- .Sx "Sed Addresses" . )
- The net result is as though each file were edited by a separate
- .Nm
- instance.
- .It Fl l
- Make output line buffered.
- .It Fl n
- By default, each line of input is echoed to the standard output after
- all of the commands have been applied to it.
- The
- .Fl n
- option suppresses this behavior.
- .It Fl r
- Same as
- .Fl E
- for compatibility with GNU sed.
- .El
- .Pp
- The form of a
- .Nm
- command is as follows:
- .Pp
- .Dl [address[,address]]function[arguments]
- .Pp
- Whitespace may be inserted before the first address and the function
- portions of the command.
- .Pp
- Normally,
- .Nm
- cyclically copies a line of input, not including its terminating newline
- character, into a
- .Em "pattern space" ,
- (unless there is something left after a
- .Dq D
- function),
- applies all of the commands with addresses that select that pattern space,
- copies the pattern space to the standard output, appending a newline, and
- deletes the pattern space.
- .Pp
- Some of the functions use a
- .Em "hold space"
- to save all or part of the pattern space for subsequent retrieval.
- .Sh "Sed Addresses"
- An address is not required, but if specified must have one of the
- following formats:
- .Bl -bullet -offset indent
- .It
- a number that counts
- input lines
- cumulatively across input files (or in each file independently
- if a
- .Fl i
- option is in effect);
- .It
- a dollar
- .Pq Dq $
- character that addresses the last line of input (or the last line
- of the current file if a
- .Fl i
- option was specified);
- .It
- a context address
- that consists of a regular expression preceded and followed by a
- delimiter. The closing delimiter can also optionally be followed by the
- .Dq I
- character, to indicate that the regular expression is to be matched
- in a case-insensitive way.
- .El
- .Pp
- A command line with no addresses selects every pattern space.
- .Pp
- A command line with one address selects all of the pattern spaces
- that match the address.
- .Pp
- A command line with two addresses selects an inclusive range.
- This
- range starts with the first pattern space that matches the first
- address.
- The end of the range is the next following pattern space
- that matches the second address.
- If the second address is a number
- less than or equal to the line number first selected, only that
- line is selected.
- The number in the second address may be prefixed with a
- .Pq Dq \&+
- to specify the number of lines to match after the first pattern.
- In the case when the second address is a context
- address,
- .Nm
- does not re-match the second address against the
- pattern space that matched the first address.
- Starting at the
- first line following the selected range,
- .Nm
- starts looking again for the first address.
- .Pp
- Editing commands can be applied to non-selected pattern spaces by use
- of the exclamation character
- .Pq Dq \&!
- function.
- .Sh "Sed Regular Expressions"
- The regular expressions used in
- .Nm ,
- by default, are basic regular expressions (BREs, see
- .Xr re_format 7
- for more information), but extended (modern) regular expressions can be used
- instead if the
- .Fl E
- flag is given.
- In addition,
- .Nm
- has the following two additions to regular expressions:
- .Pp
- .Bl -enum -compact
- .It
- In a context address, any character other than a backslash
- .Pq Dq \e
- or newline character may be used to delimit the regular expression.
- The opening delimiter needs to be preceded by a backslash
- unless it is a slash.
- For example, the context address
- .Li \exabcx
- is equivalent to
- .Li /abc/ .
- Also, putting a backslash character before the delimiting character
- within the regular expression causes the character to be treated literally.
- For example, in the context address
- .Li \exabc\exdefx ,
- the RE delimiter is an
- .Dq x
- and the second
- .Dq x
- stands for itself, so that the regular expression is
- .Dq abcxdef .
- .Pp
- .It
- The escape sequence \en matches a newline character embedded in the
- pattern space.
- You cannot, however, use a literal newline character in an address or
- in the substitute command.
- .El
- .Pp
- One special feature of
- .Nm
- regular expressions is that they can default to the last regular
- expression used.
- If a regular expression is empty, i.e., just the delimiter characters
- are specified, the last regular expression encountered is used instead.
- The last regular expression is defined as the last regular expression
- used as part of an address or substitute command, and at run-time, not
- compile-time.
- For example, the command
- .Dq /abc/s//XXX/
- will substitute
- .Dq XXX
- for the pattern
- .Dq abc .
- .Sh "Sed Functions"
- In the following list of commands, the maximum number of permissible
- addresses for each command is indicated by [0addr], [1addr], or [2addr],
- representing zero, one, or two addresses.
- .Pp
- The argument
- .Em text
- consists of one or more lines.
- To embed a newline in the text, precede it with a backslash.
- Other backslashes in text are deleted and the following character
- taken literally.
- .Pp
- The
- .Dq r
- and
- .Dq w
- functions take an optional file parameter, which should be separated
- from the function letter by white space.
- Each file given as an argument to
- .Nm
- is created (or its contents truncated) before any input processing begins.
- .Pp
- The
- .Dq b ,
- .Dq r ,
- .Dq s ,
- .Dq t ,
- .Dq w ,
- .Dq y ,
- .Dq \&! ,
- and
- .Dq \&:
- functions all accept additional arguments.
- The following synopses indicate which arguments have to be separated from
- the function letters by white space characters.
- .Pp
- Two of the functions take a function-list.
- This is a list of
- .Nm
- functions separated by newlines, as follows:
- .Bd -literal -offset indent
- { function
- function
- ...
- function
- }
- .Ed
- .Pp
- The
- .Dq {
- can be preceded by white space and can be followed by white space.
- The function can be preceded by white space.
- The terminating
- .Dq }
- must be preceded by a newline, and may also be preceded by white space.
- .Pp
- .Bl -tag -width "XXXXXX" -compact
- .It [2addr] function-list
- Execute function-list only when the pattern space is selected.
- .Pp
- .It [1addr]a\e
- .It text
- Write
- .Em text
- to standard output immediately before each attempt to read a line of input,
- whether by executing the
- .Dq N
- function or by beginning a new cycle.
- .Pp
- .It [2addr]b[label]
- Branch to the
- .Dq \&:
- function with the specified label.
- If the label is not specified, branch to the end of the script.
- .Pp
- .It [2addr]c\e
- .It text
- Delete the pattern space.
- With 0 or 1 address or at the end of a 2-address range,
- .Em text
- is written to the standard output.
- .Pp
- .It [2addr]d
- Delete the pattern space and start the next cycle.
- .Pp
- .It [2addr]D
- Delete the initial segment of the pattern space through the first
- newline character and start the next cycle.
- .Pp
- .It [2addr]g
- Replace the contents of the pattern space with the contents of the
- hold space.
- .Pp
- .It [2addr]G
- Append a newline character followed by the contents of the hold space
- to the pattern space.
- .Pp
- .It [2addr]h
- Replace the contents of the hold space with the contents of the
- pattern space.
- .Pp
- .It [2addr]H
- Append a newline character followed by the contents of the pattern space
- to the hold space.
- .Pp
- .It [1addr]i\e
- .It text
- Write
- .Em text
- to the standard output.
- .Pp
- .It [2addr]l
- (The letter ell.)
- Write the pattern space to the standard output in a visually unambiguous
- form.
- This form is as follows:
- .Pp
- .Bl -tag -width "carriage-returnXX" -offset indent -compact
- .It backslash
- \e\e
- .It alert
- \ea
- .It form-feed
- \ef
- .It carriage-return
- \er
- .It tab
- \et
- .It vertical tab
- \ev
- .El
- .Pp
- Nonprintable characters are written as three-digit octal numbers (with a
- preceding backslash) for each byte in the character (most significant byte
- first).
- Long lines are folded, with the point of folding indicated by displaying
- a backslash followed by a newline.
- The end of each line is marked with a
- .Dq $ .
- .Pp
- .It [2addr]n
- Write the pattern space to the standard output if the default output has
- not been suppressed, and replace the pattern space with the next line of
- input.
- .Pp
- .It [2addr]N
- Append the next line of input to the pattern space, using an embedded
- newline character to separate the appended material from the original
- contents.
- Note that the current line number changes.
- .Pp
- .It [2addr]p
- Write the pattern space to standard output.
- .Pp
- .It [2addr]P
- Write the pattern space, up to the first newline character to the
- standard output.
- .Pp
- .It [1addr]q
- Branch to the end of the script and quit without starting a new cycle.
- .Pp
- .It [1addr]r file
- Copy the contents of
- .Em file
- to the standard output immediately before the next attempt to read a
- line of input.
- If
- .Em file
- cannot be read for any reason, it is silently ignored and no error
- condition is set.
- .Pp
- .It [2addr]s/regular expression/replacement/flags
- Substitute the replacement string for the first instance of the regular
- expression in the pattern space.
- Any character other than backslash or newline can be used instead of
- a slash to delimit the RE and the replacement.
- Within the RE and the replacement, the RE delimiter itself can be used as
- a literal character if it is preceded by a backslash.
- .Pp
- An ampersand
- .Pq Dq &
- appearing in the replacement is replaced by the string matching the RE.
- The special meaning of
- .Dq &
- in this context can be suppressed by preceding it by a backslash.
- The string
- .Dq \e# ,
- where
- .Dq #
- is a digit, is replaced by the text matched
- by the corresponding backreference expression (see
- .Xr re_format 7 ) .
- .Pp
- A line can be split by substituting a newline character into it.
- To specify a newline character in the replacement string, precede it with
- a backslash.
- .Pp
- The value of
- .Em flags
- in the substitute function is zero or more of the following:
- .Bl -tag -width "XXXXXX" -offset indent
- .It Ar N
- Make the substitution only for the
- .Ar N Ns 'th
- occurrence of the regular expression in the pattern space.
- .It g
- Make the substitution for all non-overlapping matches of the
- regular expression, not just the first one.
- .It p
- Write the pattern space to standard output if a replacement was made.
- If the replacement string is identical to that which it replaces, it
- is still considered to have been a replacement.
- .It w Em file
- Append the pattern space to
- .Em file
- if a replacement was made.
- If the replacement string is identical to that which it replaces, it
- is still considered to have been a replacement.
- .It I
- Match the regular expression in a case-insensitive way.
- .El
- .Pp
- .It [2addr]t [label]
- Branch to the
- .Dq \&:
- function bearing the label if any substitutions have been made since the
- most recent reading of an input line or execution of a
- .Dq t
- function.
- If no label is specified, branch to the end of the script.
- .Pp
- .It [2addr]w Em file
- Append the pattern space to the
- .Em file .
- .Pp
- .It [2addr]x
- Swap the contents of the pattern and hold spaces.
- .Pp
- .It [2addr]y/string1/string2/
- Replace all occurrences of characters in
- .Em string1
- in the pattern space with the corresponding characters from
- .Em string2 .
- Any character other than a backslash or newline can be used instead of
- a slash to delimit the strings.
- Within
- .Em string1
- and
- .Em 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.
- .Pp
- .It [2addr]!function
- .It [2addr]!function-list
- Apply the function or function-list only to the lines that are
- .Em not
- selected by the address(es).
- .Pp
- .It [0addr]:label
- This function does nothing; it bears a label to which the
- .Dq b
- and
- .Dq t
- commands may branch.
- .Pp
- .It [1addr]=
- Write the line number to the standard output followed by a newline
- character.
- .Pp
- .It [0addr]
- Empty lines are ignored.
- .Pp
- .It [0addr]#
- The
- .Dq #
- and the remainder of the line are ignored (treated as a comment), with
- the single exception that if the first two characters in the file are
- .Dq #n ,
- the default output is suppressed.
- This is the same as specifying the
- .Fl n
- option on the command line.
- .El
- .Sh ENVIRONMENT
- The
- .Ev COLUMNS , LANG , LC_ALL , LC_CTYPE
- and
- .Ev LC_COLLATE
- environment variables affect the execution of
- .Nm
- as described in
- .Xr environ 7 .
- .Sh EXIT STATUS
- .Ex -std
- .Sh SEE ALSO
- .Xr awk 1 ,
- .Xr ed 1 ,
- .Xr grep 1 ,
- .Xr regex 3 ,
- .Xr re_format 7
- .Sh STANDARDS
- The
- .Nm
- utility is expected to be a superset of the
- .St -p1003.2
- specification.
- .Pp
- The
- .Fl E , I , a
- and
- .Fl i
- options, the prefixing
- .Dq \&+
- in the second member of an address range,
- as well as the
- .Dq I
- flag to the address regular expression and substitution command are
- non-standard
- .Fx
- extensions and may not be available on other operating systems.
- .Sh HISTORY
- A
- .Nm
- command, written by
- .An L. E. McMahon ,
- appeared in
- .At v7 .
- .Sh AUTHORS
- .An "Diomidis D. Spinellis" Aq dds@FreeBSD.org
- .Sh BUGS
- Multibyte characters containing a byte with value 0x5C
- .Tn ( ASCII
- .Ql \e )
- may be incorrectly treated as line continuation characters in arguments to the
- .Dq a ,
- .Dq c
- and
- .Dq i
- commands.
- Multibyte characters cannot be used as delimiters with the
- .Dq s
- and
- .Dq y
- commands.