sort_cmd.md

File Sorting

Text files can be sorted using numeric or lexical order by entire line or chosen columns. The generic command is:

$ sort [-n] [-u] [-t sep] –k key1 [–k key2] file

• -n: use numeric sorting by default (can override per key)
• -u: only keep unique lines (remove duplicates)
• -t: specify the field separator for columns
• -k: specify one or more column sort order. Each column spec can also override the numeric/lexical flag (-n)

Examples

Lexical and numeric sort on entire line. Note that records with USER_ID of 11 show up first lexically, but last numerically.

$ sort input_users.txt  | head -5
11:1234:Carol
11:5555:Carol
1:1234:Frank
2:123:Eric
3:5555:David

$ sort -n input_users.txt
USER_ID:ACCT_NUM:USER_NAME
1:1234:Frank
2:123:Eric
3:5555:David
4:5566:Bob
4:666:Bob
5:789:Carol
7:54321:Alice
7:9876:Alice
11:1234:Carol
11:5555:Carol

Get list of unique user id's

$ cut -f1 -d: < input_users.txt | sort -u -n
USER_ID
1
2
3
4
5
7
11

Sort by numeric account number (second column in input) and then by first column (numerically)

$ sort -k2n -k1n -t: input_users.txt
USER_ID:ACCT_NUM:USER_NAME
2:123:Eric
4:666:Bob
5:789:Carol
1:1234:Frank
11:1234:Carol
3:5555:David
11:5555:Carol
4:5566:Bob
7:9876:Alice
7:54321:Alice