sed - comment a matching line and x lines after it

Question

I need help with using sed to comment a matching lines and 4 lines which follows it. in a text file.

my text file is like this:

[myprocess-a]
property1=1
property2=2
property3=3
property4=4

[anotherprocess-b]
property1=gffgg
property3=gjdl
property2=red
property4=djfjf

[myprocess-b]
property1=1
property4=4
property2=2
property3=3

I want to prefix # to all the lines having text '[myprocess' and 4 lines that follows it expected output:

#[myprocess-a]
#property1=1
#property2=2
#property3=3
#property4=4

[anotherprocess-b]
property1=gffgg
property3=gjdl
property2=red
property4=djfjf

#[myprocess-b]
#property1=1
#property4=4
#property2=2
#property3=3

Greatly appreciate your help on this.

Solution 1

You can do this by applying a regular expression to a set of lines:

sed -e '/myprocess/,+4 s/^/#/' 

This matches lines with 'myprocess' and the 4 lines after them. For those 4 lines it then inserts a '#' at the beginning of the line.

(I think this might be a GNU extension - it's not in any of the "sed one liner" cheatsheets I know)

Solution 2

sed '/\[myprocess/ { N;N;N;N; s/^/#/gm }' input_file

Solution 3

Using string concatenation and default action in awk.
http://www.gnu.org/software/gawk/manual/html_node/Concatenation.html

awk '/myprocess/{f=1} f>5{f=0} f{f++; $0="#" $0} 1'  foo.txt

or if the block always ends with empty line

awk '/myprocess/{f=1} !NF{f=0} f{$0="#" $0} 1'  foo.txt

Comments

[Mausy5043]

sed: -e expression #1, char 12: unexpected ',' :-(

[Flexo]

What version of see? Odds are it's either old or not got the gnu extensions.

[Mausy5043]

sed 4.2.2. It's the Debian default so, yeah, probably missing GNU extensions

[wisbucky]

gnu documentation for this: gnu.org/software/sed/manual/html_node/Range-Addresses.html

[Vikas Goel]

How does one do it for all the lines after a matching pattern?

[Flexo]

Off the top of my head I think changing +4 to $ would do that.