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.TH TSORT 1 "Jun 28, 2007"
.SH NAME
tsort \- topological sort
.SH SYNOPSIS
.LP
.nf
\fBtsort\fR [\fIfile\fR]
.fi

.SH DESCRIPTION
.sp
.LP
The \fBtsort\fR command produces on the standard output a totally ordered list
of items consistent with a partial ordering of items mentioned in the input
\fIfile\fR.
.sp
.LP
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.
.SH OPERANDS
.sp
.LP
The following operand is supported:
.sp
.ne 2
.na
\fB\fIfile\fR\fR
.ad
.RS 8n
A path name of a text file to order. If no \fIfile\fR operand is given, the
standard input is used.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRAn example of the tsort command
.sp
.LP
The command:

.sp
.in +2
.nf
example% \fBtsort <<EOF
a b c c d e
g g
f g e f
EOF\fR
.fi
.in -2
.sp

.sp
.LP
produces the output:

.sp
.in +2
.nf
a
b
c
d
e
f
g
.fi
.in -2
.sp

.SH ENVIRONMENT VARIABLES
.sp
.LP
See \fBenviron\fR(5) for descriptions of the following environment variables
that affect the execution of \fBtsort\fR: \fBLANG\fR, \fBLC_ALL\fR,
\fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
.SH EXIT STATUS
.sp
.LP
The following exit values are returned:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.RS 6n
Successful completion.
.RE

.sp
.ne 2
.na
\fB\fB>0\fR\fR
.ad
.RS 6n
An error occurred.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
\fBlorder\fR(1), \fBattributes\fR(5), \fBenviron\fR(5), \fBstandards\fR(5)
.SH DIAGNOSTICS
.sp
.LP
\fBOdd data:\fR there are an odd number of fields in the input file.