sort.1

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th "SORT" I 5/13/75
.sh NAME
sort, usort \*- sort or merge files
.sh SYNOPSIS
.bd sort
[
.if t \fB\*-abdnrt\fIx\fR
.if n -abdnrt______x
]
[ \fB+\fIpos \fR [ \fB\*-\fIpos \fR]
] . . .
[ 
.bd \*-mo 
]
[ name ] . . .
.br
.bd usort
[
.bd \-umo
] [ name ] . . .
.sh DESCRIPTION
.it Sort
sorts
all the named files together
and writes the result on
the standard output.
The name `\*-' means
the standard input.
The standard input is also used if no input file names are given.
Thus
.it sort
may be used as a filter.
.s3
The default sort key is an entire line.
Default ordering is lexicographic in ASCII collating sequence,
except that lower-case letters are considered
the same as the corresponding upper-case letters.
Non-ASCII bytes are ignored.
The ordering is affected by the flags
.if t \fB\*-abdnrt\fR,
.if n .it abdnrt,
one or more of which may appear:
.s3
.lp +4 4
\fBa\fR	Do not map lower case letters.
.s3
.lp +4 4
\fBb\fR	Leading blanks (spaces and tabs) are not included in fields.
.s3
.lp+4 4
\fBd\fR	`Dictionary' order: only letters, digits and blanks
are significant in ASCII comparisons.
.s3
.lp +4 4
\fBn\fR	An initial numeric string,
consisting of optional minus sign,
digits and optionally included decimal point,
is sorted by arithmetic value.
.s3
.lp+4 4
\fBr\fR	Reverse the sense of comparisons.
.s3
.lp +4 4
\fBt\fIx\fR	Tab character between fields is
.it x.
.s3
.i0
Selected parts of the line, specified by
\fB+\fIpos\fR
and
\fB\*-\fIpos\fR,
may be used as sort keys.
.it Pos 
has the form
.it m.n,
where
.it m
specifies a number of fields to skip,
and 
.it n
a number of characters to skip further into the next field.
A missing
.it \\.n
is taken to be 0.
\fB+\fIpos\fR denotes the beginning of the key;
\fB\*-\fIpos\fR denotes the first position after the key
(end of line by default).
The ordering rule may be overridden for a particular key
by appending one or more of the flags
.bd abdnr
to
\fB+\fIpos\fR.
.s3
When no tab character has been specified,
a field consists of
nonblanks and any preceding blanks.
Under the
.bd \*-b
flag, leading blanks are excluded from a field.
When a tab character has been specified,
a field is a
string ending with a tab character.
.s3
.i0
When keys are specified,
later keys are compared only when all earlier ones compare equal.
Lines that compare equal are ordered
with all bytes significant.
.s3
These flag arguments are also understood:
.s3
.lp +4 4
\fB\*-m\fR	Merge only, the input files are already sorted.
.s3
.lp +4 4
\fB\*-o\fR	The next argument is the name of an output file
to use instead of the standard output.
This file may be the same as one of the inputs,
except under the merge flag \fB\*-m\fR.
.i0
.s3
.it Usort
is a somewhat specialized version of
.it sort
which accepts no collating sequence options:
order is always
plain ASCII.
It also strips out the second and following copies
of duplicated lines.
A
.it u
flag prevents this stripping.
.it Usort
also understands
the
.it m
and
.it o
options in the same way as
.it sort.
.sh FILES
/usr/tmp/stm???
.sh BUGS