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 NAME     
 SYNOPSIS     
 |  |  |  | sed [ −gln ] [ −e script ] [ −f sfile ] [ file ... ] 
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 DESCRIPTION     
 |  |  |  | Sed copies the named files (standard input default) to the standard
    output, edited according to a script of commands. The −f option
    causes the script to be taken from file sfile; these options accumulate.
    If there is just one −e option and no −f’s, the flag −e may be
    omitted. The −n option suppresses the default output; −g causes
    all substitutions to be
    global, as if suffixed g. The −l option causes sed to flush its
    output buffer after every newline. 
    
    
    A script consists of editing commands, one per line, of the following
    form: 
 In normal operation sed cyclically copies a line of input into
    a pattern space (unless there is something left after a D command),
    applies in sequence all commands whose addresses select that pattern
    space, and at the end of the script copies the pattern space to
    the standard output (except under −n) and deletes the pattern
    space. 
    
    
    An address is either a decimal number that counts input lines
    cumulatively across files, a $ that addresses the last line of
    input, or a context address, /regular-expression/, in the style
    of regexp(7), with the added convention that \n matches a newline
    embedded in the pattern space. 
    
    
    A command line with no addresses selects every pattern space.
    
    
    
    A command line with one address selects each pattern space that
    matches the address. 
    
    
    A command line with two addresses selects the inclusive range
    from the first pattern space that matches the first address through
    the next pattern space that matches the second. (If the second
    address is a number less than or equal to the line number first
    selected, only one line is selected.) Thereafter the process is
    repeated, looking again for the first
    address. 
    
    
    Editing commands can be applied to non-selected pattern spaces
    by use of the negation function ! (below). 
    
    
    An argument denoted text consists of one or more lines, all but
    the last of which end with \ to hide the newline. Backslashes
    in text are treated like backslashes in the replacement string
    of an s command, and may be used to protect initial blanks and
    tabs against the stripping that is done on every script line.
    
    
    
    An argument denoted rfile or wfile must terminate the command
    line and must be preceded by exactly one blank. Each wfile is
    created before processing begins. There can be at most 120 distinct
    wfile arguments.|  |  |  | [address [, address] ] function [argument ...] | 
 a\
 text       Append. Place text on the output before reading the next input
    line.
 b label     Branch to the : command bearing the label. If label is
    empty, branch to the end of the script.
 c\
 text       Change. Delete the pattern space. With 0 or 1 address or at
    the end of a 2-address range, place text on the output. Start
    the next cycle.
 d         Delete the pattern space. Start the next cycle.
 D         Delete the initial segment of the pattern space through the first
    newline. Start the next cycle.
 g         Replace the contents of the pattern space by the contents of
    the hold space.
 G         Append the contents of the hold space to the pattern space.
 h         Replace the contents of the hold space by the contents of the
    pattern space.
 H         Append the contents of the pattern space to the hold space.
 i\
 text       Insert. Place text on the standard output.
 n         Copy the pattern space to the standard output. Replace the pattern
    space with the next line of input.
 N         Append the next line of input to the pattern space with an embedded
    newline. (The current line number changes.)
 p         Print. Copy the pattern space to the standard output.
 P         Copy the initial segment of the pattern space through the first
    newline to the standard output.
 q         Quit. Branch to the end of the script. Do not start a new cycle.
 r rfile      Read the contents of rfile. Place them on the output before
    reading the next input line.
 s/regular-expression/replacement/flags
 
 t label     Test. Branch to the : command bearing the label if any
    substitutions have been made since the most recent reading of
    an input line or execution of a t. If label is empty, branch to
    the end of the script.|  |  |  | |  |  |  | Substitute the replacement string for instances of the regular-expression
            in the pattern space. Any character may be used instead of /.
            For a fuller description see regexp(7). Flags is zero or more
            of g     Global. Substitute for all non-overlapping instances of the regular
            expression rather than just the first one.
 p     Print the pattern space if a replacement was made.
 w wfileWrite. Append the pattern space to wfile if a replacement
            was made.
 
 | 
 | 
 w         wfile
 
 x         Exchange the contents of the pattern and hold spaces.|  |  |  | |  |  |  | Write. Append the pattern space to wfile. 
 | 
 | 
 y/string1/string2/
 
 !function    Don’t. Apply the function (or group, if function is {)
    only to lines not selected by the address(es).|  |  |  | |  |  |  | Transform. Replace all occurrences of characters in string1 with
            the corresponding character in string2. The lengths of string1
            and string2 must be equal. 
 | 
 | 
 : label     This command does nothing; it bears a label for b and t
    commands to branch to.
 =         Place the current line number on the standard output as a line.
 {         Execute the following commands through a matching } only when
    the pattern space is selected.
 
 |  |  |  | |  |  |  | An empty command is ignored. 
 | 
 | 
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 EXAMPLES     
 |  |  |  | sed 10q file 
 sed '/^$/d'|  |  |  | Print the first 10 lines of the file. 
 | 
 
 sed 's/UNIX/& system/g'|  |  |  | Delete empty lines from standard input. 
 | 
 
 sed 's/ *$//       drop trailing blanks|  |  |  | Replace every instance of UNIX by UNIX system. | 
 /^$/d              drop empty lines
 s/    */\           replace blanks by newlines
 /g
 /^$/d' chapter*
 
 nroff −ms manuscript | sed '|  |  |  | Print the files chapter1, chapter2, etc. one word to a line. | 
 ${
 
 }|  |  |  | if last line of file is empty, print it 
 | 
 //N               if current line is empty, append next line
 /^\n$/D'           if two lines are empty, delete the first
 
 |  |  |  | Delete all but one of each group of empty lines from a formatted
        manuscript. 
 | 
 | 
 SOURCE     
 SEE ALSO    
 |  |  |  | ed(1), grep(1), awk(1), lex(1), sam(1), regexp(7) L. E. McMahon, ‘SED -- A Non-interactive Text Editor’, Unix Research
    System Programmer’s Manual, Volume 2.
 
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 BUGS     
 |  |  |  | If input is from a pipe, buffering may consume characters beyond
    a line on which a q command is executed. 
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