man/man2/chmod.2

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.he 'CHMOD (II)'3/15/72'CHMOD (II)'
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NAME            chmod  --  change mode of file
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SYNOPSIS        sys chmod; name; mode  / chmod = 15.
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DESCRIPTION     The file whose name
is given as the null-terminated string pointed to by name\b\b\b\b____
has its mode changed to mode\b\b\b\b____.
Modes are constructed by or\b\b__ing together some
combination of the following:
.sp
.in +3
 01 write, non-owner
 02 read, non-owner
 04 write, owner
 10 read, owner
 20 executable
 40 set user ID on execution
.in -3
.sp
Only the owner of a file (or the super-user) may change the mode.
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SEE ALSO        chmod(I)
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DIAGNOSTICS     Error bit
(c-bit) set if name\b\b\b\b____ cannot be found or if current user
is neither the owner of the file nor the super-user.
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BUGS            --