.fp 5 CW

.de Af

.ds ;G \\*(;G\\f\\$1\\$3\\f\\$2

.if !?\\$4?? .Af \\$2 \\$1 "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"

..

.de aF

.ie ?\\$3?? .ft \\$1

.el \{\

.ds ;G \&

.nr ;G \\n(.f

.Af "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"

\\*(;G

.ft \\n(;G \}

..

.de L

.aF 5 \\n(.f "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"

..

.de LR

.aF 5 1 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"

..

.de RL

.aF 1 5 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"

..

.de EX		\" start example

.ta 1i 2i 3i 4i 5i 6i

.PP

.RS 

.PD 0

.ft 5

.nf

..

.de EE		\" end example

.fi

.ft

.PD

.RE

.PP

..

.TH STRPERM 3

.SH NAME

strperm \- evaluate file permission expression

.SH SYNOPSIS

.L "int strperm(char* s, char** e, int p)"

.SH DESCRIPTION

.I strperm

applies a file permission expression in the nul-terminated string

.I s

to the initial file permission mask

.IR p .

The new permission mask is returned.

If 

.I e

not 0 then

.I *e

is set to point to the first unrecognized character in

.IR s .

.PP

A tape device specification is composed of one or more

.I who-op-permission

terms separated by

.BR , .

.I who

selects portions of the permission bits and may be any combination of:

.TP 3

.B u

the user permission bits;

.TP

.B g

the group permission bits;

.TP

.B o

the `other' permission bits;

.TP

.B a

all permission bits.

.PP

If omitted, all permission bits are selected.

.I op

specifies how the original permission

.I p

is to be modified:

.TP 3

.B +

.br

.ns

.B |

the new bits are set in

.IR p ;

.TP 3

.B \-

the new bits are cleared in

.IR p ;

.TP

.B &

the new bits are and'd with

.IR p ;

.TP

.B =

the select bits in

.I p

are set equal to the new bits

.PP

A permission expression term may also be an octal number.

Octal specifications are inherently non-portable.

Refer to

.IR chmod (1)

for an explanation of this form.

.SH "SEE ALSO"

chmod(1), ls(1), strmode(3)