User group concept:
In Linux, each user belongs to a group, outside the group is not independent of Eng,
Documents Related concepts:
the owner; where the group; other groups; the user to change a file's group;
ls view the file details
# Ls -ahl Anaconda3- 5.3 . 1 -Linux-x86_64. sh rw-r - r--. 1 wolf 638M July 3 05 : 57 Anaconda3- 5.3 . 1 -Linux-x86_64. sh
The first character represents the file (-), directory (d), a link (l)
After the character triads (r = 4, w = 2, x = 1):
Owner of the file permissions rw- The first group read, write,
A second set of user permissions r-- and the owner of the file is read the same group,
The third group r-- not with the user's permission to file owner is reading the same group,
1 shows the number of files connected
wolf represents the user
wolf represents user's group;
638M July * .sh file size, date, name
## change file permissions
1，chmod 755 filename
2, chmod u = rwx, g = rx, o = rx filename supra u = user permissions, g = permissions user's group, o = different sets of permissions to other users
3, chmod ux, g + w filename to remove the permissions abc performed by the user, increasing the write permission group
4, chmod a + r filename add read access to all users
## to modify the file owner and user groups
1, chown xiaoming abc: abc change the owner of xiaoming
2, chgrp root abc: changes the group belongs root abc
3, chown root ./abc: changes the owner of this directory is the root abc
4, chown -R root ./abc: abc change the owner of the directory and all files and directories below the root
Example: to establish user groups group1 and group2 two, and three user dennis, daniel, abigale, and allocates the first two users in a user group group1, after a user group assignment in group2
The groupadd named group1 # # group2 the groupadd # the useradd - G named group1 Dennis # the useradd - G named group1 Dani # the useradd - G group2 sjhh # Set Password # the passwd Dennis # sjhh user to change the group consisting group2 becomes named group1 # the usermod -g named group1 sjhh