Shell Script: Calculate Tomorrow’s Date on Unix
A couple of readers, upon reading this article to calculate yesterday’s date in a shell script, have requested for a similar script that can be used to calculate tomorrow’s date.
Tag Archives: linux
How to Intrepret Shadow Passwords in UNIX
In modern UNIX and Linux systems, user passwords are encrypted and stored in the /etc/shadow file. On BSD systems, the passwords are kept in the /etc/master.passwd file. The encrypted password field in the file contains more than just the encrypted password, it contains additional information.
How to Determine the Linux Distribution
Linux is a very customisable UNIX like operating system. To date, there are more than a couple of dozen Linux distributions available, based on this Wikipedia list.
Shell Script: Calculate Yesterday’s Date on UNIX
There are times when you will need to calculate yesterday’s date in a UNIX shell script to run some date sensitive cron jobs. There are currently no standard command line tools in UNIX to perform such date arithmetic.
How to Login to an Expired root Account in Solaris
If your organisation has password aging policy set for your UNIX servers, there is a possibility that the root account may also get locked out due to the existence of an expiry date set in the /etc/shadow file. Once the root account is locked, all jobs (cron, etc) that require root privileges may start to fail. To unlock the root account on a SUN SPARC machine, you will need to:
Recursive FTP from the Command Line
The default command line ftp client in most UNIX distributions do not support recursive downloads, even though recursive downloads is a basic feature in most GUI based ftp clients. But if you do not have access to the X-Windows or GUI, there are alternative ways to achieve the same result from the command line.
UNIX Terminal Session Management
Have you ever encountered the dreaded “Connection closed by foreign host” message when you were logged into a remote server via SSH and you were in the middle of some important task? You have most probably just lost your session and you will have to start your task all over again. Well, you can prevent this from happening by using the screen command available in most UNIX and Linux distributions.
How to Disable a CPU Core
Multi-core CPUs pack multiple processors into a single chip thus allowing multiple threads to run at once. Most of the time, this is a good thing. But at times, for example, when you need to run some legacy applications that are not compatible with multi-core processing, you may be required to disable the cores.
Mount ISO Image Under Linux
An ISO image is a disk image file of an optical disc. The format of the disc is defined by the International Organization for Standardization (ISO). ISO 9660 is the most commonly used optical disc file system. An ISO image can also contain UDF file system which is backwards compatible with ISO 9660.
Enable Ubuntu root Account
Ubuntu Linux distribution, by default, disables the root account. To run a command with root privileges, sudo has to be used before the command.
