Most POSIX commands that have recursive directory traversal option (ls, chmod, chgrp, chmod, cp, rm) have -R for that. rm also has -r because that's what it was initially, long before POSIX. Now, the behaviour varies when symlinks are found in walking down the tree.

2017年7月7日 · OCTAL-MODE FILE... chmod [OPTION]... --reference=RFILE FILE... DESCRIPTION. This manual page documents the GNU version of chmod. chmod changes the file mode bits of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number repre‐ senting the bit pattern for the new mode bits.

2015年2月1日 · chgrp canard .; chmod g+s . Further, if we were to place the two commands on separate lines, then the remaining semicolon is unneeded: chgrp canard . chmod g+s . Documentation. For more information, see man chmod. Also, wikipedia has tables summarizing the chmod command options.

chmod u=rwx filename will set the user's permissions and leave the others as they are. You can even "add" or "substract" permissions: chmod g-x filename will remove the group's x permission, and. chmod o+w filename will add write permission for others. To set SUID, SGID, and sticky bit use the s and t permissions: chmod u+s filename-- sets SUID

2019年3月27日 · The man page of chmod covers that. u stands for user. g stands for group. o stands for others. a stands for all. That means that chmod u+x somefile will grant only the owner of that file execution permissions whereas chmod +x somefile is the same as chmod a+x somefile. The chmod man page says:

chmod changes the file mode bits of each given file according to mode, which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new mode bits.

2017年5月12日 · The classic Unix permissions set by chmod (read/write/execute, user/group/other) have existed for a lot longer than ACL. If ACL had existed from the start then there wouldn't be a chmod as we know it. However, since chmod has existed for a very long time, many applications call it, many archive formats support the classic permissions, etc.

You can set the suid bit using chmod, eg chmod 4755 which will give a file give the normal permissions 755 does (rwxr-xr-x) and add the suid bit to give rwsr-xr-x. You can clear the setuid bit by issuing a normal chmod command with a 0 prepended to it. For example, to set permissions back to rwxr-xr-x you would use chmod 0755.

2012年5月31日 · The standard UNIX way to show that a number is octal is to start it with a zero. GNU chmod will assume the mode you're giving it is octal anyway, but it's safest to prepend the zero. Finally, if you see a + at the end of the modestring:-rwxr-xr-x+ then that means the file has extended permissions, and you'll need more than chmod.

2022年7月22日 · a=rX sets the read bit for everyone, and the executable bit on directories; see What is a capital X in posix / chmod? for details. It clears all other bits. It clears all other bits. (This can’t be combined with a-x , because X here would set the executable bit for any non-directory with an executable bit set too; applying a-x first ensures ...