sort

Documentation

Overview

Package sort implements the sort builtin command.

sort — sort lines of text files

Usage: sort [OPTION]... [FILE]...

Write sorted concatenation of all FILE(s) to standard output. With no FILE, or when FILE is -, read standard input.

Accepted flags:

-r, --reverse
    Reverse the result of comparisons (sort descending).

-n, --numeric-sort
    Compare according to string numerical value.

-u, --unique
    Output only the first of an equal run.

-k, --key=KEYDEF
    Sort via a key definition; KEYDEF is F[.C][OPTS][,F[.C][OPTS]].

-t, --field-separator=SEP
    Use SEP as the field separator.

-b, --ignore-leading-blanks
    Ignore leading blanks when finding sort keys.

-f, --ignore-case
    Fold lowercase to uppercase for comparisons.

-d, --dictionary-order
    Consider only blanks and alphanumeric characters.

-c
    Check whether input is sorted; exit 1 if not.

-C, --check=silent
    Like -c but do not print the diagnostic line.

-s, --stable
    Stabilize sort by disabling last-resort comparison.

-h, --help
    Print usage to stdout and exit 0.

Rejected flags (unsafe):

-o FILE (writes to filesystem)
-T DIR  (writes temp files)
--compress-program (executes a binary)

Exit codes:

0  Success (or input is sorted when using -c/-C).
1  Error, or input is NOT sorted when using -c/-C.

Memory safety:

sort must buffer all input before producing output. A maximum of
MaxLines (1,000,000) lines is enforced to prevent OOM. Per-line cap
of MaxLineBytes (1 MiB) is enforced via the scanner. All loops check
ctx.Err() at each iteration to honour the shell's execution timeout.

Index

• Constants
• Variables

Constants

const MaxLineBytes = 1 << 20 // 1 MiB

MaxLineBytes is the per-line buffer cap for the line scanner.

const MaxLines = 1_000_000

MaxLines is the maximum number of lines sort will buffer. Beyond this the command errors out to prevent unbounded memory growth.

const MaxTotalBytes = 5 * 1024 * 1024 // 5 MiB

MaxTotalBytes is the cumulative byte cap across all input lines. This prevents OOM when many lines are each below MaxLineBytes but collectively consume excessive memory — especially in sort chains where N concurrent sort instances each hold their full input buffer simultaneously.

Variables

var Cmd = builtins.Command{
	Name:        "sort",
	Description: "sort lines of text files",
	MakeFlags:   registerFlags,
}

Cmd is the sort builtin command descriptor.