sed
is the Stream EDitor. It can do a whole pile of really cool things, but the most common is text replacement.
The s,%,$,g
part of the command line is the sed
command to execute. The s
stands for substitute, the ,
characters are delimiters (other characters can be used; /
, :
and @
are popular). The %
is the pattern to match (here a literal percent sign) and the $
is the second pattern to match (here a literal dollar sign). The g
at the end means to g
lobally replace on each line (otherwise it would only update the first match).
Here sed
is replacing all occurrences of %
with $
in its standard input.
As an example
$ echo 'foo%bar%' | sed -e 's,%,$,g'
will produce "foo$bar$".
It reads Hello World
(cat
), replaces all (g
) occurrences of %
by $
and (over)writes it to /etc/init.d/dropbox
as root.
sed is a stream editor. I would say try man sed.If you didn't find this man page in your system refer this URL:
Source: Stackoverflow.com