Manipulating texts and lines: SORT, UNIQ, PASTE, JOIN, SPLIT

 SORT

Basically, alphabetical sorting.

$ sort <filename>
Sort the lines in the specified file, according to the characters at the beginning of each line

$ cat file1 file2 | sort
Combine the two files, then sort the lines and display the output on the terminal

$ sort -r <filename>
Sort the lines in reverse order

$ sort -k 3 <filename>
Sort the lines by the 3rd field on each line instead of the beginning

UNIQ

Remove the duplicates in the same line of a file

$ sort file1 file2 | uniq > file3
or
$ sort -u file1 file2 > file3

$ uniq -c filename
counts the numbers of duplicates

PASTE

$ paste -d ':' file1 file2
Merges the rows of file1 and file2 separating them with ":" instead of a TAB space.

-s
Outputs the data in horizontal rows instead of vertical.

JOIN

$ join file1 file2
Merges the rows of file1 and file2 overwriting the same fileds.

SPLIT

$ split file segment-file
Splits file1 into equal-sized segments named segment-filexx of 1000 lines each (default number). Where xx is the number related to each segment file.