umask

هذا الجزء لم يُترجم بعد. أنت ترى النص الإنجليزي.

ماذا يفعل

Programs create new files with 666 (rw for all) and new directories with 777. The umask removes bits from this: with umask 022, files get 644 and directories 755.

umask is a shell built-in: it changes only the current shell and its children. Make it permanent in ~/.bashrc (one user) or a file in /etc/profile.d/ (all users). Services use the UMask= setting in their systemd unit.

طريقة الكتابة

umask [-p] [-S] [MODE]

الخيارات 3

الأكثر استخدامًا

MODE: The new mask, as a number (027) or in letters (u=rwx,g=rx,o=).
-S: Show the mask in letters (as the permissions that stay).
-p: Show it in a form you can use again as a command.

أمثلة 11

$ مستخدم عادي# بصلاحية root (أو مع sudo)

1Show the mask
```
$umask
0022
```
The RHEL default.
2Show it in letters
```
$umask -S
u=rwx,g=rx,o=rx
```
The rights that new directories get.

3Set a safer mask for this shell

$umask 027
$touch f; mkdir d; ls -ld f d
-rw-r-----. 1 student student 0 Oct 25 10:30 f
drwxr-x---. 2 student student 6 Oct 25 10:30 d

Others get nothing.

4Make it permanent for one user
```
$echo "umask 027" >> ~/.bashrc
```
Valid from the next shell.
5Make it permanent for all users
```
#echo "umask 027" > /etc/profile.d/umask.sh
```
Read at every login shell.
6Very private files
```
$umask 077
```
Files 600, folders 700.
7Set the umask with letters
```
$umask u=rwx,g=rx,o=
$umask
0027
```
Same as 027.
8Use a mask for one command only
```
$(umask 077; openssl genrsa -out private.key 4096)
```
The key file is private from the start (no time window).
9Set the umask of a service
```
#systemctl edit myapp
```
Add [Service] and UMask=0027 — shell files do not affect services.
10Check the default of new users
```
$grep -E '^(UMASK|HOME_MODE)' /etc/login.defs
UMASK		022
HOME_MODE	0700
```
login.defs sets the umask for login and the mode of new home folders.
11Why a file never gets x from the umask
```
$umask 000; touch x; ls -l x
-rw-rw-rw-. 1 student student 0 Oct 25 10:35 x
```
Files start at 666; add x with chmod.

انتبه

The umask is not a chmod: it only affects files created later.
A default ACL on a directory replaces the umask for new files in it.

الملفات

~/.bashrc: umask for one user.
/etc/profile.d/*.sh: umask for all login shells.
/etc/login.defs: UMASK and HOME_MODE.

`umask`

ماذا يفعل

طريقة الكتابة

الخيارات 3

أمثلة 11

1Show the mask

2Show it in letters

3Set a safer mask for this shell

4Make it permanent for one user

5Make it permanent for all users

6Very private files

7Set the umask with letters

8Use a mask for one command only

9Set the umask of a service

10Check the default of new users

11Why a file never gets x from the umask

انتبه

الملفات

الدليل الكامل

ماذا يفعل

طريقة الكتابة

الخيارات 3

أمثلة 11

1Show the mask

2Show it in letters

3Set a safer mask for this shell

4Make it permanent for one user

5Make it permanent for all users

6Very private files

7Set the umask with letters

8Use a mask for one command only

9Set the umask of a service

10Check the default of new users

11Why a file never gets x from the umask

انتبه

الملفات

أوامر مرتبطة

مُستخدم في هذه الدروس

الدليل الكامل

`umask`