Allow specific user permission to read/write my folder

If you are using Linux with a relatively modern filesystem (ext3/ext4, btrfs, ntfs), this can be done with POSIX ACLs:

1. Enable ACLs for the filesystem. This is only necessary for ext3 and ext4 on kernels older than 2.6.38. All other filesystems that support ACLs enable them automatically.

   mount -o remount,acl /
   tune2fs -o acl /dev/<partition>
   

2. Give tom access to the folder:

   setfacl -m user:tom:rwx /home/samantha/folder
   

If the OS or the filesystem does not support ACLs, another way is to use groups.

1. Create a group.

   • Some Linux distributions create a separate group for each user: tom would automatically be in a group also named tom.

   • If not, create a group. This should work on Linux...

     groupadd tom
     gpasswd -a tom tom
     

     ...and this - on BSD:

     groupadd tom
     usermod -G tom tom
     

2. chgrp the directory to that group, and give permissions with chmod:

    chgrp tom /home/samantha/folder
    chmod g+rwx /home/samantha/folder
   

Add both users to a common group. Make that group own the directory, and assign group permissions as needed.

• How to create a new Group on UNIX
• How To Add a User to a Group on UNIX
• Group Permissions for Files and Directories