I have a file called test.sh. I've used chown to set it's owner to user1.
chown user1 test.shThen I play with chmod options to see if I understand them correctly.
chmod 400 test.shI can read the file but cannot modify or execute it.
chmod 200 test.shI can modify the file through command line but cannot read or execute it.
chmod 100 test.shI should be able to execute but not modify or read the file. But I get a permission denied error everytime I try to execute without sudo.
What am I doing wrong here?
32 Answers
You can also try this.
This will add execute permission to owner
chmod u+x fileThis will remove execute permission from owner if he had it.
chmod u-x filefirst character means who will be affected by this change.
- u = user - owner
- g = group - owning group
- o = other - anyone
- a = all - same as ugo
second character means if you will add or remove permissions
- + = add permission
- - = remove permission
- = = set permission and overwrite
third character means which permission to apply
for files:
- r = read - display content of file, copy
- w = write - change content of file, remove, rename
- x = execute - run script, program ...
for folders:
- r = read - display content of folder
- w = write - create, remove files from directory
- x = execute - cd into directory
If you want to add write permission for owner to all files in folder, run
chmod u+w -R folderYou can also combine them, so following are valid
chmod ugo+r file
chmod ug+rx fileBasic permissions:
- Read:
r––→ 4 - Write:
–w–→ 2 - Execute:
––x→ 1
Most used combinations:
- Read:
r––→ 4+0+0 = 4 - Read and exec:
r–x→ 4+0+1 = 5 - Read and write:
rw–→ 4+2+0 = 6 - Read, write and exec:
rwx→ 4+2+1 = 7
Further reading:
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