chmod 700 -R ~ - is it safe?

I'm thinking of doing 'chmod 700 -R ~'. Can it be dangerous? What can happen what I don't expect? Also, is there any way to keep all files on $HOME to be -rwx------?

Anon

Posted 2013-10-30T21:50:27.700

Reputation: 61

1You don't have to do a recursive chmod. chmod 700 ~ will keep all prying eyes out of your home directory. – mtak – 2014-06-20T14:51:33.953

@mtak: Ummm, Did you read the existing comments? – Scott – 2014-06-20T15:31:05.207

How about doing chmod 700 /home/* instead of doing recursive. Since if access into parent directory's permission is denied, other users' will not able to access their sub-directories. If recursion is required after a new folder created under home ~ we have to change its permission. It might be difficult to keep track of all the new folders and update their permission. @Scott – alper – 2018-06-03T18:50:57.380

3Why not just chmod go-rx ~? No need to recurse. (FWIW, some systems might not like it, e.g. when users publish web sites using ~/Sites or ~/www or something like that -- then the http server needs access to ~ -- but you'd know it if you did that). – Daniel Beck – 2013-10-30T22:05:49.773

Of course, if somebody made a copy of one of Anon’s world-readable files yesterday, there’s no way of recovering it. But what if somebody made a hard link to one of his files? chmoding the home directory won’t affect that; he needs recursion to make the linked file private. – Scott – 2013-10-30T22:33:12.513

Answers

The main problem I can think of is that that command will set the execute bit on all files, even those that aren’t executable. So, if you have a file called foo, and someday you want to do cat foo or print foo and you accidentally type just foo, the shell will try to execute foo; i.e., interpret it as a shell script. This will probably just explode in your face harmlessly, but if foo contains anything that looks like a shell command, you could get harmful results.

A lesser issue is that if you have a file that you want to preserve, and last year you did a chmod 444 to protect it from yourself, the chmod 700 will restore your write bit, and make it easier for you to clobber the file accidentally.

The solution to both issues is to do chmod go= -R ~ or chmod go-rwx -R ~, which will turn off all bits for group and others, but leave your access alone.

Scott

Posted 2013-10-30T21:50:27.700

Reputation: 17 653

1Could I run chmod 700 /home/* instead of doing recursive. Since access into parent directory's permission is denied, other users' will not able to access their sub-directories. @Scott – alper – 2018-06-03T18:47:04.233

Kind of old now but you can chmod 700 for folders and chmod 600 files and it would solve the issue of adding the execute bit on all regular files (you need execute on folders to ls).

find ~ -type d -print0 | xargs -0 chmod 700
find ~ -type f -print0 | xargs -0 chmod 600

Brendan Stennett

Posted 2013-10-30T21:50:27.700

Reputation: 1

3This GNU coreutils command has the same effect: chmod -R ~ go-rwx,u+rwX. It first removes group and world permissions, then adds read and write to the user and execute to directories. Warning: some files are expected to have an execute bit (like those in ~/bin/ or node_modules/bin/). – Lekensteyn – 2014-06-20T13:42:37.580