In Unix-like operating systems, sort is a standard command line program that prints the lines of its input or concatenation of all files listed in its argument list in sorted order. Sorting is done based on one or more sort keys extracted from each line of input. By default, the entire input is taken as sort key. Blank space is the default field separator.
Contents
- History
- Sort a file in alphabetical order
- Sort by number
- Columns or fields
- Sort on multiple fields
- Sorting a pipe delimited file
- Sorting a tab delimited file
- Sort in reverse
- Sort in random
- Sorting algorithm
- References
The "-r" flag will reverse the sort order.
History
Sort was part of Version 1 Unix. By Version 4 Ken Thompson had modified it to use pipes, but sort retained an option to name the output file because it was used to sort a file in place. In Version 5, Thompson invented "-" to represent standard input.
Sort a file in alphabetical order
$ cat phonebookSmith, Brett 555-4321Doe, John 555-1234Doe, Jane 555-3214Avery, Cory 555-4132Fogarty, Suzie 555-2314$ sort phonebookAvery, Cory 555-4132Doe, Jane 555-3214Doe, John 555-1234Fogarty, Suzie 555-2314Smith, Brett 555-4321Sort by number
The -n option makes the program sort according to numerical value. The du command produces output that starts with a number, the file size, so its output can be piped to sort to produce a list of files sorted by (ascending) file size:
Columns or fields
Use the -k option to sort on a certain column. For example, use "-k 2" to sort on the second column). In old versions of sort, the +1 option made the program sort on the second column of data (+2 for the third, etc.). This usage is deprecated.
Sort on multiple fields
The -k m,n option lets you sort on a key that is potentially composed of multiple fields (start at column m, end at column n):
Here the first sort is done using column 2. -k2,2 specifies sorting on the key starting and ending with column 2. If -k2 is used instead, the sort key would begin at column 2 and extend to the end of the line, spanning all the fields in between. The n stands for 'numeric ordering'. -k1,1 dictates breaking ties using the value in column 1, sorting alphabetically by default. Note that bob, an and chad have the same quota and are sorted alphabetically in the final output.
Sorting a pipe delimited file
$ sort -t'|' -k2 zipcodeAdam|12345Wendy|23456Bob|34567Sam|45678Joe|56789Sorting a tab delimited file
Sorting a file with tab separated values requires a tab character to be specified as the column delimiter. This illustration uses the shell's dollar-quote notation to specify the tab as a C escape sequence.
Sort in reverse
The -r option just reverses the order of the sort:
Sort in random
The GNU implementation has a -R/--random-sort option based on hashing; this is not a full random shuffle because it will sort identical lines together. A true random sort is provided by the Unix utility shuf.
Sorting algorithm
The implementation in GNU Core Utilities, used on Linux, employs the merge sort algorithm.