tsort

- topological sort

Synopsis

tsort [file]

Description

The tsort command produces on the standard output a totally ordered list of items consistent with a partial ordering of items mentioned in the input file.

The input consists of pairs of items (non-empty strings) separated by blanks. Pairs of different items indicate ordering. Pairs of identical items indicate presence, but not ordering.

Operands

The following operand is supported:

file

A path name of a text file to order. If no file operand is given, the standard input is used.

Examples

Example 1 An example of the tsort command

The command:

example% tsort <<EOF
a b c c d e
g g
f g e f
EOF

produces the output:

a
b
c
d
e
f
g

Environment Variables

See environ(5) for descriptions of the following environment variables that affect the execution of tsort: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.

Exit Status

The following exit values are returned:

0

Successful completion.

>0

An error occurred.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

lorder(1), attributes(5), environ(5), standards(5)

Diagnostics

Odd data: there are an odd number of fields in the input file.