Linux – Recursive chmod to 644 Where Current Permission is 755

chmodlinuxpermissions

I copied a project directory to a portable hard disk, wiped my laptop and copied the project back, but now git reports loads of changes due to files that previously had 644 permission changing to 755.

I could recursively chmod all files and directories to 644, but then I get a load more changes in git (so looks like not everything was 644 previously). Is there any way to chmod only files that have 755 permissions?

Best Answer

The documentation for find (see man find) writes,

-perm mode File's permission bits are exactly mode (octal or symbolic). [...] See the EXAMPLES section for some illustrative examples.

So you can match files and change their permissions like this

find path/to/files -type f -perm 0755 -exec echo chmod 0644 {} +

Remove the echo when you are comfortable that it's showing you what you expect, and run it again.

Related Solutions

Chmod Command – How to Use chmod -R 644 on ~/Documents

You need to have the execute bit set on a directory to allow the affected user to enter it and access files and directories inside, and you've removed it (your command removes the execute bit from both the files and the folders). There is information about this here. The following command should fix it:

find ~/Documents -type d -exec chmod a+x {} +

Why use `chmod 644` instead of `chmod u=rw,go=r,…`

Using the octal codes has two advantages I can think of, neither of which is that huge:

They're shorter, easier to type.
A few things only understand them, and if you routinely use them you'll not be scratching your head (or running to documentation) when you run into one. E.g., you have to use octal for chmod in Perl or C.

Sometimes really simple utilities won't handle the "friendly" versions; especially in non-GNU userlands.

Further, some utilities spit out octal. For example, if you run umask to see what your current umask is, it'll spit it out in octal (though in bash, umask -S does symbolic).

So, in short, I'd say the only reason to prefer them is to type fewer characters, but that even if you elect not to use them, you should know how they map so that you can figure out an octal code if you run into one of the things that only does octal. But you don't need to immediately know that 5 maps to rx, you only need to be able to figure that out.

Best Answer

Related Solutions

Chmod Command – How to Use chmod -R 644 on ~/Documents

Why use `chmod 644` instead of `chmod u=rw,go=r,…`

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