5.06 Filter Utilities

Filters – are commands that output a modified version of their input (sort and wc)

sort - sort lines of text files. (by default will “fold” upper and lower case characters)

Options:

-b blank # ignores leading spaces and tabs

-c check # checks whether files are already sorted and if so, produces no output

-d dictionary # sorts in dictionary output

-f fold (alphabetically) # ignores upper/lowercase differences

-g general numeric # sorts according to general numeric value

-n numeric # sorts according to a string numeric value

-r reverse # sorts in reverse order

-tc separate # separates fields with character defined by c. Default is tab.

-u unique # sorts so that identical files in input file appear only once in output

wc - print the number of bytes, words, and lines in files

Options:

-c bytes # displays the character count only

-l lines # displays the line count only

-w words # displays the word count only

uniq - removes duplicate lines from a file

Options:

-c count

-d duplicate

-D all duplicate

-i ignore

-u unique

Example:

diff - compares two files and display all the difference two files or directories to the screen

head, tail - display the beginning or the end of a file

Options:

-n num Number

-q quiet

-v verbose

Example: Using command head to display first 20 lines of the file

dpaste - merge lines of files

Options:

-d delimiter (reuse characters form LIST instead of TABS

-s serial – paste one file at a time instead of in parallel

Example:

cut - removes sections from each line of files

Options:

-b list bytes list

-c list characterslist

-d c delimiter (Default c)

-f list fields

Example: $ cut -c1-19 pets

Example: $ cut -f1,3 pets (columns)

Example:

paste - allows to combine files

Options:

- replace a file name with standard input

dchar separates columns with the char defined in char instead of a tab

-s merges lines from a file one file at a time