Using awk grep sed

grep does not alter a file, it only finds matches while awk and sed are text processors.

awk is mostly used for data extraction and reporting. sed is a stream editor. Each one of them has its own functionality and specialties.

sed

Things that you can accomplish using RegEx within the Vi editor on text files can also be accomplished at the command line with sed.

The most basic form is to use sed as a simple search and replace.

sed 's/windows/linux/'

example: process text file by removing blanks, unwanted lines, and duplicates

Get rid of all lines of text containing numerical stats

sed -i '/[0-9]/d' Razor-Fen.txt

Get rid of all empty lines containing no characters

sed -i '/^\s*$/d' Razor-Fen.txt

Get rid of all duplicate lines

sed -i '$!N; /^\(.*\)\n\1$/!P; D' Razor-Fen.txt

grep

example: rgrep

rgrep is grep -r or recursive grep

If you want to search all text files within all subfolders for a particular matching string, the syntax might not be what you would think

For example, rgrep string *.txt will not search though all text files under the current directory, the correct syntax would be:

rgrep -s string --include \*.txt

Here is an example that searches for multiple specific types

rgrep -i --include \*.h --include \*.cpp CP_Image ~/path[12345]

awk

The awk utility is useful for changing data files and generating reports.

By default Awk behaves like 'cat' in that it prints every line of data from the specified file.

awk '{print}' inventory.txt