filesystems

Symlinks vs Hardlinks and how to create them

In a previous article I covered a little bit about Symlinks and Hardlinks but I never really explained what they are or how to create them. Today I am going to cover how to create both Symlinks and Hardlinks and what the difference is between the two. What are Symlinks and Hardlinks Hard Links In Linux when you perform an listing in a directory the listing is actually is a list of references that map to an inode.

EMC PowerPath: superblock could not be read

Recently while working on a system that uses EMC PowerPath, I ran into a little issue after rebooting. The Issue fsck.ext3: No such file or directory while trying to open /dev/emcpowera1 /dev/emcpowera1: The superblock could not be read or does not describe a correct ext2 filesystem. The Cause The root cause of this issue is pretty simple when a Linux system boots it performs file system checks on file systems listed within the /etc/fstab file.

ACL: Using Access Control Lists on Linux

Access Control Lists aka ACL's are one of those obscure Linux tools that isn't used every day; and if you find yourself using ACL's every day than you probably have a very complicated Linux environment. A few years ago I had an engineer tell me “Any thing you want to solve with ACL's can be solved with standard unix permissions” and while he may have just been justifying why he didn't know ACL's very well.

Stat: Detailed information about a file

Stat is a command that I never knew about until somewhat recently but afterwards have had more and more reasons to use it. When run against a file stat will show detailed information about the file, this information can be extremely useful and I want to highlight some of the information I've found useful from stat. $ stat rsync.out File: `rsync.out' Size: 696506 Blocks: 1368 IO Block: 4096 regular file Device: fc00h/64512d Inode: 13862 <strong>Links: 1</strong> Access: (0644/-rw-r--r--) Uid: ( 1000/madflojo) Gid: ( 1000/madflojo) Access: 2012-05-21 19:28:00.