chmod.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 CHMOD I 2/8/75
.sh NAME
chmod \*- change mode
.sh SYNOPSIS
.bd chmod
octal file ...
.sh DESCRIPTION
The octal mode
replaces the mode of each of the files.
The mode is constructed from the OR of the
following modes:
.s3
.lp +10 7
4000	set user ID on execution
.lp +10 7
2000	set group ID on execution
.lp +10 7
1000	sticky bit for shared, pure-procedure programs (see below)
.lp +10 7
0400	read by owner
.lp +10 7
0200	write by owner
.lp +10 7
0100	execute (search in directory) by owner
.lp +10 7
0070	read, write, execute (search) by group
.lp +10 7
0007	read, write, execute (search) by others
.s3
.i0
Only the owner of a file (or the super-user) may change its mode.
.s3
If an executable file is set up for sharing (``\*-n'' option
of
.it "ld (I)"
), then mode 1000 prevents the system from
abandoning the swap-space image of the program-text portion
of the file when its last user
terminates.
Thus when the next user of the file executes it,
the text need not be read from the file
system but can simply be swapped in,
saving time.
Ability to set this bit is restricted to the super-user
since swap space is consumed
by the images; it is only worth while for heavily used commands.
.s3
.sh "SEE ALSO"
ls (I),
chmod (II)
.sh BUGS