[SOLVED] Command line - show surrounding context lines in a file around known exact line number

Issue

How to output N(e.g. 2) lines surrounding a specific known line number(e.g. 5) in a file?

cat >/tmp/file <<EOL
foo

bar

baz

qux

quux
EOL

# some command

Expected output:

bar

baz

qux

Solution

If you know the line and number of lines in advance and thus you are able to compute the number of the first line and number of the last line you might use simple GNU sed command, for example

sed -n '3,7p' file.txt

will output 3rd, 4th, 5th, 6th and 7th line of file.txt.

If you wish to change the line number then I would use GNU AWK following way

awk 'BEGIN{n=5}NR==n-2,NR==n+2' file.txt

Explanation: I set n to 5 then I use Range to select lines from n-2th line (inclusive) to n+2th line (inclusive), no action is provided which is equivalent of giving {print}.

Answered By - Daweo

Answer Checked By - David Goodson (WPSolving Volunteer)