Tag Archives: linux

ls command with a long listing format

When we execute the ls command with a long listing format, what does this mean?

ls -l filename

-l option of a ls command will instruct ls to display output in a long listing format which means that instead of output containing only a name(s) of file or directory the ls command will produce additional information.

linux ls command

Example:

ls -l file
-rw-rw-r--. 1 root swat 0 Jan 26 09:30 file1

From the output above we can deduct a following information:

  • -rw-rw-r- permissions
  • 1 : number of linked hard-links
  • root: owner of the file
  • swat: to which group this file belongs to
  • 0: size
  • Jan 26 09:30 modification/creation date and time
  • file1: file/directory name

To answer your question we will look more closely at the permissions part of ls long listing format output:

- -rw-rw-r--

The permissions part can be broken down to 4 parts. First part in this example is “-” which specifies that this is a regular file. Other common uses are:

  • l this specifies symbolic links
  • d stands for directory
  • c stands for character file

Next three parts are also called octets and they define a permissions applied to this file. First octet ( -rw- ) defines a permission for a file owner. In this case owner has read and write permissions. Second part ( rw- ) defines read and write permissions defined for a group. And the last part defines read-only permissions for others ( everyone else ).

From permissions listed as:

lrwxrwxrwx

we can conclude that this particular file is a symbolics link pointing to yet another file somewhere within a file system. It lists full permissions for an owner, group and everyone else. Although it has full permissions for everyone it does not mean that the file it is pointing to will also have the same permissions ( in most cases it does not !). We can check the file name to see where this symbolic link is pointing to. For example this X executable binary points to Xorg in the same directory:

$ ls -l X
lrwxrwxrwx. 1 root root 4 Feb 22 10:52 X -> Xorg
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save username password in putty to auto-login

For some versions of Putty it’s as simple as:
putty.exe root@example.com -pw mypasswordforexamplecom
For those using Windows, you can simply create a shortcut and pass in those parameters. For example:
  1. Create a shortcut on desktop to putty.exe
  2. Rename the shortcut to “PuTTY – example.com”
  3. Right-click shortcut and choose Properties
  4. Modify the target similar to: “C:\Program Files\PuTTY\putty.exe” user@example.com -pw password
  5. You can also use IP Address of host in place of domain host name
  6. Click OK
Otherwise, you need to use a public key as explained here : “Creating and Copying Your Key-Pair in PuTTY SSH Client”.
 
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