Tutorial details
Difficulty level Easy
Root privileges Yes
Requirements None
Est. reading time N/A
How do I check swap (page) usage under Sun / Oracle Solaris Unix operating systems using command line options? How do I see virtual memory statistics including used and total swap space?
[continue reading…]

I‘m using dump command to backup file systems to tape and remote server. However, I’m not able to find any option that will allow me to exclude files or directories from backup. How do I force UNIX / Linux / FreeBSD dump command to exclude selected files (such as /var/cache or /usr/basejails) which I don’t want to backup?
[continue reading…]

Q. Iā€™m new to Linux and how do I examine filesystem and identify regular files or directories?

A. Both Linux and UNIX comes with ls command for examining the filesystem. You can use ls command to look at the filesystem. ls command can display:
=> Character devices
=> Regular files
=> Sym links (symbolic links)
=> Directories
=> Pipes
=> Sockets
=> Block devices

ls command examples

Display /etc directory files, enter:
$ ls /etc
When invoked without any arguments, ls lists the files in the current working directory:
$ ls
Use -l (long option) to lists filenames, sizes, permissions, type and all other information:
$ ls /etc/passwd

-rw-r--r-- 1 root root 2453 Jul 17 16:25 /etc/passwd

See Linux / UNIX file permissions for more information


A directory is marked with a d as the first letter of the permissions field:
ls -ld /etc

drwxr-xr-x 88 root root 12288 Aug  5 23:46 /etc

Symbolic link

A symbolic link is marked with an l (lower case L) as the first letter of the permissions string:
ls -l /bin/nisdomainname

lrwxrwxrwx 1 root root 8 Jul 10 08:50 /bin/nisdomainname -> hostname


  • A named pipe is marked with a p as the first letter of the permissions string.
  • A socket is marked with a s as the first letter of the permissions string.
  • A character device is marked with a c as the first letter of the permissions strings. (ls -l /dev/console)
  • A block device is marked with a b (ls -l /dev/sdb1).