283 lines
9.2 KiB
Groff
283 lines
9.2 KiB
Groff
.TH sed 1 "March 30, 2006"
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.SH NAME
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sed \- the stream editor
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.SH SYNOPSIS
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sed [-n] [-g] [-e script ] [-f sfile ] [ file ] ...
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.SH DESCRIPTION
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Sed copies the named files (standard input default) to the standard
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output, edited according to a script of commands.
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.P
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An -e option supplies a single edit command from the next argument;
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if there are several of these they are executed in the order in which
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they appear. If there is just one -e option and no -f 's, the -e flag
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may be omitted.
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.P
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An -f option causes commands to be taken from the file "sfile"; if
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there are several of these they are executed in the order in which
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they appear; -e and -f commands may be mixed.
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.P
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The -g option causes sed to act as though every substitute command
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in the script has a g suffix.
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.P
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The -n option suppresses the default output.
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.P
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A script consists of commands, one per line, of the following form:
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[address [, address] ] function [arguments]
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Normally sed cyclically copies a line of input into a current text
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buffer, then applies all commands whose addresses select the buffer in
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sequence, then copies the buffer to standard output and clears it.
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.P
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The -n option suppresses normal output (so that only p and w output
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is done). Also, some commands (n, N) do their own line reads, and some
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others (d, D) cause all commands following in the script to be skipped
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(the D command also suppresses the clearing of the current text buffer
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that would normally occur before the next cycle).
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.P
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It is also helpful to know that there's a second buffer (called the `hold
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space' that can be copied or appended to or from or swapped with
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the current text buffer.
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.P
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An address is: a decimal numeral (which matches the line it numbers where line
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numbers start at 1 and run cumulatively across files), or a `$' that addresses
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the last line of input, or a context address, which is a `/regular
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expression/', in the style of ed (1) modified thus:
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.P
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.TP 5
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(1)
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The escape sequence `\\n' matches a newline embedded in the buffer,
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and `\\t' matches a tab.
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.TP 5
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(2)
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A command line with no addresses selects every buffer.
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.TP 5
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(3)
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A command line with one address selects every buffer that matches
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that address.
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.TP 5
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(4)
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A command line with two addresses selects the inclusive range from
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the first input buffer that matches the first address through the
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next input buffer that matches the second. (If the second address
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is a number less than or equal to the line number first selected,
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only one line is selected.) Once the second address is matched sed
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starts looking for the first one again; thus, any number of these
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ranges will be matched.
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.P
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The negation operator '!' can prefix a command to apply it to every
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line not selected by the address(es).
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.P
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In the following list of functions, the maximum number of addresses
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permitted for each function is indicated in parentheses.
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.P
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An argument denoted "text" consists of one or more lines, with all
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but the last ending with `\' to hide the newline.
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.P
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Backslashes in text are treated like backslashes in the replacement
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string of an `s' command and may be used to protect initial whitespace
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(blanks and tabs) against the stripping that is done on every line of
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the script.
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.P
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An argument denoted "rfile" or "wfile" must be last on the command
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line. Each wfile is created before processing begins. There can be at
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most 10 distinct wfile arguments.
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.TP 5
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a "text" (1)
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Append. Place text on output before reading the next input line.
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.TP 5
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b "label" (2)
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Branch to the `:' command bearing the label. If no label is given,
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branch to the end of the script.
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.TP 5
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c "text" (2)
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Change. Delete the current text buffer. With 0 or 1 address, or at
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the end of a 2-address range, place text on the output. Start the next
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cycle.
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.TP 5
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d (2)
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Delete the current text buffer. Start the next cycle.
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.TP 5
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D (2)
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Delete the first line of the current text buffer (all chars up to the
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first newline). Start the next cycle.
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.TP 5
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g (2)
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Replace the contents of the current text buffer with the contents of
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the hold space.
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.TP 5
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G (2)
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Append the contents of the hold space to the current text buffer.
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.TP 5
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h (2)
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Copy the current text buffer into the hold space.
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.TP 5
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H (2)
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Append a copy of the current text buffer to the hold space.
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.TP 5
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i "text" (1)
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Insert. Place text on the standard output.
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.TP 5
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l (2)
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List. Sends the pattern space to standard output. A "w" option may
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follow as in the s command below. Non-printable characters expand to:
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\\b -- backspace (ASCII 08)
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\\t -- tab (ASCII 09)
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\\n -- newline (ASCII 10)
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\\r -- return (ASCII 13)
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\\e -- escape (ASCII 27)
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\\xx -- the ASCII character corresponding to 2 hex digits xx.
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.TP 5
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Dump. Hex-dump the pattern space to standard output.
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.TP 5
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n (2)
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Copy the current text buffer to standard output. Read the next line
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of input into it.
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.TP 5
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N (2)
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Append the next line of input to the current text buffer, inserting
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an embedded newline between the two. The current line number changes.
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.TP 5
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p (2)
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Print. Copy the current text buffer to the standard output.
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.TP 5
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P (2)
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Copy the first line of the current text buffer (all chars up to the
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first newline) to standard output.
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.TP 5
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q (1)
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Quit. Branch to the end of the script. Do not start a new cycle.
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.TP 5
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r "rfile" (1)
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Read the contents of rfile. Place them on the output before reading
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the next input line.
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.TP 5
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s /regular expression/replacement/flags (2)
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Substitute the replacement for instances of the regular expression
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in the current text buffer. Any character may be used instead of `/'.
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For a fuller description see ed (1).
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Flags is zero or more of the following:
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g -- Global. Substitute for all nonoverlapping instances of the string
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rather than just the first one.
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p -- Print the pattern space if a replacement was made.
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w -- Write. Append the current text buffer to a file argument as in a
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w command if a replacement is made. Standard output is used if no
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file argument is given
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.TP 5
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t "label" (2)
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Branch-if-test. Branch to the : command with the given label if any
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substitutes have been made since the most recent read of an input line
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or execution of a `t'or `T'. If no label is given, branch to the end
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of the script.
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.TP 5
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T "label" (2)
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Branch-on-error. Branch to the : command with the given label if no
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substitutes have succeeded since the last input line or t or T command.
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Branch to the end of the script if no label is given.
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.TP 5
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w "wfile" (2)
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Write. Append the current text buffer to wfile .
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.TP 5
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W "wfile" (2)
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Write first line. Append first line of the current text buffer
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to wfile.
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.TP 5
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x (2)
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Exchange the contents of the current text buffer and hold space.
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.TP 5
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y /string1/string2/ (2)
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Translate. Replace each occurrence of a character in string1 with
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the corresponding character in string2. The lengths of these strings
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must be equal.
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.TP 5
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! "command" (2)
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All-but. Apply the function (or group, if function is `{') only to
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lines not selected by the address(es).
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.TP 5
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: "label" (0)
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This command does nothing but hold a label for `b' and `t' commands
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to branch to.
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.TP 5
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= (1)
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Place the current line number on the standard output as a line.
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.TP 5
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{ (2)
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Execute the following commands through a matching `}' only when the
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current line matches the address or address range given.
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.P
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An empty command is ignored.
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.P
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.SH PORTABILITY
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This tool was reverse-engineered from BSD 4.1 UNIX sed, and (as far
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as the author's knowledge and tests can determine) is compatible with
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it. All documented features of BSD 4.1 sed are supported.
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.P
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One undocumented feature (a leading 'n' in the first comment having
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the same effect as an -n command-line option) has been omitted.
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.P
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The following bugs and limitations have been fixed:
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.TP 5
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*
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There is no hidden length limit (40 in BSD sed) on w file names.
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.TP 5
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*
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There is no limit (8 in BSD sed) on the length of labels.
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.TP 5
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*
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The exchange command now works for long pattern and hold spaces.
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.P
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The following enhancements to existing commands have been made:
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.TP 5
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*
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a, i commands don't insist on a leading backslash-\\n in the text.
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.TP 5
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*
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r, w commands don't insist on whitespace before the filename.
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.TP 5
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*
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The g, p and P options on s commands may be given in any order.
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.P
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Some enhancements to regular-expression syntax have been made:
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.TP 5
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*
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\\t is recognized in REs (and elswhere) as an escape for tab.
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.TP 5
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*
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In an RE, + calls for 1..n repeats of the previous pattern.
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.P
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The following are completely new features:
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.TP 5
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*
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The l command (list, undocumented and weaker in BSD)
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.TP 5
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The 'L' command (hex dump).
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.TP 5
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*
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The W command (write first line of pattern space to file).
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.TP 5
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*
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The T command (branch on last substitute failed).
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.TP 5
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*
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Trailing comments are now allowed on command lines.
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.P
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In addition, sed's error messages have been made more specific and
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informative.
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.P
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The implementation is also significantly smaller and faster than
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BSD 4.1 sed. It uses only the standard I/O library and exit(3).
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.P
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.SH SEE ALSO
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.P
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ed(1), grep(1), awk(1), lex(1), regexp(5)
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.P
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.SH AUTHOR
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Eric S. Raymond <esr@snark.thyrsus.com> and Rene Rebe <rene@exactcode.de>.
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This program is distributed under the GPL.
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