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[address1 [, address2 ]]s/ pattern / replacement / [flags ]

Substitute replacement for pattern on each addressed line. If pattern addresses are used, the pattern // represents the last pattern address specified. Any delimiter may be used. Use \ within pattern or replacement to escape the delimiter. The following flags can be specified:


Replace all instances of pattern on each addressed line, not just the first instance.


Print the line if a successful substitution is done. If several successful substitutions are done, sed prints multiple copies of the line.

w file

Write the line to file if a replacement was done. A maximum of 10 different files can be opened.


Replace n th instance of pattern on each addressed line. n is any number in the range 1 to 512, and the default is 1.


Here are some short, commented scripts:

# Change third and fourth quote to ( and ):

# Remove all quotes on a given line:

# Remove first colon and all quotes; print resulting lines:

# Change first "if" but leave "ifdef" alone:
/ifdef/!s/if/   if/

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