diffutils: ed Scripts

 
 2.5.1 'ed' Scripts
 ------------------
 
 'diff' can produce commands that direct the 'ed' text editor to change
 the first file into the second file.  Long ago, this was the only output
 mode that was suitable for editing one file into another automatically;
 today, with 'patch', it is almost obsolete.  Use the '--ed' ('-e')
 option to select this output format.
 
    Like the normal format (⇒Normal), this output format does not
 show any context; unlike the normal format, it does not include the
 information necessary to apply the diff in reverse (to produce the first
 file if all you have is the second file and the diff).
 
    If the file 'd' contains the output of 'diff -e old new', then the
 command '(cat d && echo w) | ed - old' edits 'old' to make it a copy of
 'new'.  More generally, if 'd1', 'd2', ..., 'dN' contain the outputs of
 'diff -e old new1', 'diff -e new1 new2', ..., 'diff -e newN-1 newN',
 respectively, then the command '(cat d1 d2 ... dN && echo w) | ed - old'
 edits 'old' to make it a copy of 'newN'.
 

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