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Find Longest Line in a File

awk ' { if ( length > x ) { x = length } }END{ print x }' file.txt

Perform Floating Point Calculations

awk can be used for complex calculations, for example:

awk 'BEGIN {printf "%.3f\n", sin(30 * atan2(0, -1)/180)}'

will calculate $\sin(30^\circ)=sin(30rad * \frac{\pi}{180})$ and return:

0.500

Since awk does not have a constant for $\pi$ , we use atan2(0, -1) instead.

Suppose you have a file input containing data separated by delimiters such as:

variable = value

or:

variable = value

The following command can be used to obtain value:

awk -F"[ \t]*[=][ \t]*" '{ print $2 }' input

To remove all duplicates from file.txt without sorting, issue:

awk '!x[$0]++' file.txt

Given a file with the contents:

Q: What is this?
A: This is a FAQ!

and you would like to achieve:

Q: What is this? A: This is a FAQ!

then the following awk one liner:

awk 'NR%2{printf "%s ",$0;next;}1' yourFile

will merge all the lines in a file by two.