Confusion in chmod options

Question

I have a file called test.sh. I've used chown to set it's owner to user1.

chown user1 test.sh

Then I play with chmod options to see if I understand them correctly.

chmod 400 test.sh

I can read the file but cannot modify or execute it.

chmod 200 test.sh

I can modify the file through command line but cannot read or execute it.

chmod 100 test.sh

I 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?

score 3 · Answer 1 · edited Aug 03 '17 at 15:21

You can also try this.

This will add execute permission to owner

chmod u+x file

This will remove execute permission from owner if he had it.

chmod u-x file

first character means who will be affected by this change.

second character means if you will add or remove permissions

third character means which permission to apply

for files:

for folders:

If you want to add write permission for owner to all files in folder, run

chmod u+w -R folder

You can also combine them, so following are valid

chmod ugo+r file
chmod ug+rx file

pa4080 · Accepted Answer · 2017-08-03T12:55:24.207

Basic permissions:

Most used combinations:

2 Answers2