sort

sort

The sort command in Unix and Linux is used to sort lines of text files. It can sort the lines alphabetically, numerically, or based on various other criteria. The sort command can also handle complex sorting tasks with various options to customize its behavior.

Basic Usage

The basic syntax for the sort command is:

sort [options] [file...]

• file: The file(s) to be sorted. If no file is specified, sort reads from standard input.

Examples

Sorting a File Alphabetically

To sort the lines in a file alphabetically:

sort file.txt

Sorting a File and Saving the Output

To sort a file and save the sorted output to another file:

sort file.txt > sorted_file.txt

Options

Sorting in Reverse Order

To sort in reverse order, use the -r option:

sort -r file.txt

Sorting Numerically

To sort numerically, use the -n option. This is useful when dealing with numbers:

sort -n numbers.txt

Sorting by a Specific Field

To sort by a specific field (column), use the -k option followed by the field number. Fields are typically separated by spaces or tabs:

sort -k 2 file.txt

This command sorts file.txt by the second field.

Sorting by Multiple Fields

You can sort by multiple fields by specifying multiple -k options:

sort -k 2 -k 3 file.txt

This command sorts by the second field, and if there are ties, it sorts by the third field.

Ignoring Case

To perform a case-insensitive sort, use the -f option:

sort -f file.txt

Removing Duplicates

To remove duplicate lines, use the -u option:

sort -u file.txt

Advanced Options

Sorting with a Custom Delimiter

To sort based on a custom delimiter, use the -t option followed by the delimiter character. For example, to sort by a comma-separated value (CSV) file:

sort -t ',' -k 2 file.csv

Sorting by Human-Readable Numbers

If your file contains human-readable numbers (e.g., 1K, 2M), use the -h option to sort these correctly:

sort -h file.txt

Sorting with Stable Sort

To ensure that the original order is preserved for equal elements, use the -s option:

sort -s file.txt

Sorting by Month

If your file contains dates with month names and you want to sort them correctly, use the -M option:

sort -M dates.txt

Practical Use Cases

Sorting a List of Names

To sort a list of names alphabetically:

sort names.txt

Sorting Log Files by Date

Assuming your log file entries start with a date, you can sort them chronologically:

sort -k 1,1 -k 2,2 log.txt

Sorting Disk Usage

To sort the output of the du command (disk usage) by size:

du -h | sort -h

Combining with Other Commands

Sorting and Removing Duplicates

To sort a file and remove duplicate lines, you can combine sort with uniq:

sort file.txt | uniq

Or use the -u option directly with sort:

sort -u file.txt

Sorting Pipelined Input

You can pipe the output of other commands into sort:

ls -l | sort -k 5 -n

This command lists files in the current directory and sorts them by size (fifth column) numerically.

Summary

The sort command is a powerful and versatile tool for sorting lines of text in Unix and Linux. By understanding and using its various options, you can sort files alphabetically, numerically, and in many other ways. This command is essential for data processing, log analysis, and numerous other tasks.

help

Usage: sort [OPTION]... [FILE]...
  or:  sort [OPTION]... --files0-from=F
Write sorted concatenation of all FILE(s) to standard output.

With no FILE, or when FILE is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
Ordering options:

  -b, --ignore-leading-blanks  ignore leading blanks
  -d, --dictionary-order      consider only blanks and alphanumeric characters
  -f, --ignore-case           fold lower case to upper case characters
  -g, --general-numeric-sort  compare according to general numerical value
  -i, --ignore-nonprinting    consider only printable characters
  -M, --month-sort            compare (unknown) < 'JAN' < ... < 'DEC'
  -h, --human-numeric-sort    compare human readable numbers (e.g., 2K 1G)
  -n, --numeric-sort          compare according to string numerical value
  -R, --random-sort           shuffle, but group identical keys.  See shuf(1)
      --random-source=FILE    get random bytes from FILE
  -r, --reverse               reverse the result of comparisons
      --sort=WORD             sort according to WORD:
                                general-numeric -g, human-numeric -h, month -M,
                                numeric -n, random -R, version -V
  -V, --version-sort          natural sort of (version) numbers within text

Other options:

      --batch-size=NMERGE   merge at most NMERGE inputs at once;
                            for more use temp files
  -c, --check, --check=diagnose-first  check for sorted input; do not sort
  -C, --check=quiet, --check=silent  like -c, but do not report first bad line
      --compress-program=PROG  compress temporaries with PROG;
                              decompress them with PROG -d
      --debug               annotate the part of the line used to sort,
                              and warn about questionable usage to stderr
      --files0-from=F       read input from the files specified by
                            NUL-terminated names in file F;
                            If F is - then read names from standard input
  -k, --key=KEYDEF          sort via a key; KEYDEF gives location and type
  -m, --merge               merge already sorted files; do not sort
  -o, --output=FILE         write result to FILE instead of standard output
  -s, --stable              stabilize sort by disabling last-resort comparison
  -S, --buffer-size=SIZE    use SIZE for main memory buffer
  -t, --field-separator=SEP  use SEP instead of non-blank to blank transition
  -T, --temporary-directory=DIR  use DIR for temporaries, not $TMPDIR or /tmp;
                              multiple options specify multiple directories
      --parallel=N          change the number of sorts run concurrently to N
  -u, --unique              with -c, check for strict ordering;
                              without -c, output only the first of an equal run
  -z, --zero-terminated     line delimiter is NUL, not newline
      --help     display this help and exit
      --version  output version information and exit

KEYDEF is F[.C][OPTS][,F[.C][OPTS]] for start and stop position, where F is a
field number and C a character position in the field; both are origin 1, and
the stop position defaults to the line's end.  If neither -t nor -b is in
effect, characters in a field are counted from the beginning of the preceding
whitespace.  OPTS is one or more single-letter ordering options [bdfgiMhnRrV],
which override global ordering options for that key.  If no key is given, use
the entire line as the key.  Use --debug to diagnose incorrect key usage.

SIZE may be followed by the following multiplicative suffixes:
% 1% of memory, b 1, K 1024 (default), and so on for M, G, T, P, E, Z, Y.

*** WARNING ***
The locale specified by the environment affects sort order.
Set LC_ALL=C to get the traditional sort order that uses
native byte values.

GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Report any translation bugs to <https://translationproject.org/team/>
Full documentation <https://www.gnu.org/software/coreutils/sort>
or available locally via: info '(coreutils) sort invocation'