V10/man/man1/sort.1

.TH SORT 1 
.CT 1 files
.SH NAME
sort \- sort and/or merge files
.SH SYNOPSIS
.B sort
[
.BI -cmusMbdf\&inrt x
]
[
.B -o
.I output
]
[
.I option ...
]
[
.I file ...
]
.SH DESCRIPTION
.I Sort\^
sorts
lines of all the
.I files
together and writes the result on
the standard output.
The name
.B -
means
the standard input.
If no input files are named, the standard input is sorted.
.PP
The default sort key is an entire line.
Default ordering is
lexicographic by bytes in machine
collating sequence.
The ordering is affected globally by the following options,
one or more of which may appear.
.TP
.B -b
Ignore leading white space (spaces and tabs) in field comparisons.
.TP
.B -d
`Phone directory' order: only letters, digits and white space
are significant in string comparisons.
.TP
.B -f
Fold lower case
letters onto upper case.
.TP
.B -i
Ignore characters outside the
.SM ASCII
range 040-0176
in string comparisons.
.TP
.B -n
An initial numeric string,
consisting of optional white space, optional sign, and
a nonempty string of digits with optional decimal point,
is sorted by value.
.TP
.B -g
Numeric, like
.BR -n ,
with
.BR e -style
exponents allowed.
.TP
.B -M
Compare as month names.
The first three
characters after optional white space
are folded to lower case and compared.
Invalid fields compare low to
.LR jan .
.TP
.B -r
Reverse the sense of comparisons.
.TP
.BI -t x\^
`Tab character' separating fields is
.IR x .
.TP
.BI -k " pos1" , pos2
Restrict the sort key to a string beginning at
.I pos1\^
and ending at
.IR pos2 .
.I Pos1\^
and
.I pos2\^
each have the form
.IB m . n ,
optionally followed by one or more of the flags
.BR Mbdfginr ;
.I m\^
counts fields from the beginning of the line and
.I n\^
counts characters from the beginning of the field.
If any flags are present they override all the global
ordering options for this key.
If
.BI \&. n\^
is missing from 
.I pos1,
it is taken to be 1; if missing from
.IR pos2, 
it is taken to be the end of the field.
If 
.I pos2
is missing, it is taken to be end of line.
.PP
Under option
.BI -t x\^
fields are strings separated by
.IR x ;
otherwise fields are
non-empty strings separated by white space.
White space before a field
is part of the field, except under option
.BR -b .
A
.B b
flag may be attached independently to
.IR pos1
and
.IR pos2.
.PP
When there are multiple sort keys, later keys
are compared only after all earlier keys
compare equal.
Except under option 
.BR -s ,
lines with all keys equal are ordered
with all bytes significant.
.PP
Single-letter options may be combined into a single
string, such as
.BR -cnrt: .
The option combination
.B -di
and the combination of
.B -n
with any of
.BR -diM 
are improper.
Posix argument conventions are supported.
.PP
These option arguments are also understood:
.TP
.B -c
Check that the single input file is sorted according to the ordering rules;
give no output unless the file is out of sort.
.TP
.B -m
Merge; the input files are already sorted.
.TP
.B -u
Unique.  Keep only the first of two lines 
that compare equal on all keys.
Implies
.BR -s .
.TP
.B -s
Stable sort.
When all keys compare equal, preserve input order.
Unaffected by
.BR -r .
.TP
.BI -o " output
Place output in a designated file
instead of on the standard output.
This file may be the same as one of the inputs.
The option may appear among the
.I file
arguments, except after 
.BR -- .
.TP
.BI -T " tempdir
Put temporary files in
.I tempdir
rather than in (the default)
.BR /usr/tmp .
.TP
.BI -ymemory
Suggests using the specified number of 
bytes of internal store to tune performance;
an unspecified
.I memory
size is taken to be huge.
.TP
.BI + pos1 " -" pos2
Classical alternative to
.BR -k ,
with counting from 0 instead of 1, and
.I pos2
designating next-after-last instead of last character of the key.
A missing character count in
.I pos2
means 0, which in turn excludes any 
.B -t
tab character from the end of the key.
Thus
.B "+1\ -1.3"
means the same as 
.B -k\ 2,2.3
and
.B "+1r\ -3"
means the same as
.BR "-k\ 2r,3" .
.ig
.TP
.BI -z recsize
Provide for abnormally large records;
useful only with
.B -c
and
.B -m
..
.SH EXAMPLES
.TP
.L sort -u -k1f -k1 list
Print in alphabetical order all the unique spellings
in a list of words
where capitalized words differ from uncapitalized.
.TP
.L sort -t: -k3n /etc/passwd
Print the password file
.RI ( passwd (5))
sorted by userid
(the third colon-separated field).
.TP
.L sort -umM dates
Print the first instance of each month in an already sorted file.
.SH FILES
.F /usr/tmp/stm???
.SH SEE ALSO
.IR comm (1),
.IR join (1),
.IR uniq (1),
.IR look (1)
.SH DIAGNOSTICS
.I Sort
comments and exits with non-zero status for various trouble
conditions and for disorder discovered under option
.BR -c .
.SH BUGS
The never-documented default
.IR pos1 =0
for cases such as
.B sort -1
has been abolished.
.br
Trouble (e.g. crash or file-system overflow) encountered 
while overwriting an input with
.BR -o 
is irrecoverable.