IT Systems, Networks, Security and Education
This is post 11 of 11 in the series “The Linux Command Line” The first principle of file creation is that when you, as a specific user, create a file, it will be owned by you, and your default group will have some default permissions set on that file. Remember the User – Group – …
Continue reading “Linux: Creating and Deleting Directories and Files”
This is post 9 of 30 in the series “Introduction to Python” PEP 8 Python Enhancement Proposals (PEPs) dictate the rules for coding in Python. (Several other languages could use something like this.) Use this link: http://introtopython.org/lists_tuples.html#What-is-a-PEP? … but scroll up to the beginning of the section “Coding Style: PEP 8” (the link in the …
This is post 9 of 11 in the series “The Linux Command Line” Both sudo and su are highly dangerous. The sudo command is used to run a following command as the super-user. Think “super-user do.” It lets regular users do rootly thing, like: sudo cat /etc/shadow You’ll be prompted for a password: Your Password. …
This is post 8 of 11 in the series “The Linux Command Line” Examine root’s user profile and PATH characteristics. Become root: sudo su – Enter the command: ifconfig as root, and you’ll see your IP address (among other things). Just to be sure, run: whoami And while you’re at it, check your (root’s) group …
This is post 7 of 11 in the series “The Linux Command Line” When a new user is created, the default files and directories that are created are stored in /etc/skel. This directory can be modified to fit your needs. Modifications will only affect new users; they do not change anything for existing users.
This is post 3 of 11 in the series “The Linux Command Line” Boot, login, and start Secure Telnet/Secure Shell or PuTTY. Log in with your UNM user name and password. Check Your Shell Command: echo $SHELL Your answer may be: /bin/sh # the Bourne shell /bin/csh # the C shell /bin/bash # the Bourne …
This is post 13 of 19 in the series “[ Shell Scripting ]” Arguments For our first trick, we’re going to write a script that shows us how arguments are dealt with by scripts. Start a new script called args. (Notice that it doesn’t have to be “args.sh”.) Create the script: #!/bin/bash if [ $# …
This is post 12 of 19 in the series “[ Shell Scripting ]” The Bourne/bash shell supports a variety of conditionals, loops and other flow control operations. You’ll use these often. if The if statement is a simple conditional. Its syntax is: if condition ; then commands [elif condition ; then commands]… [else commands] fi …
This is post 11 of 19 in the series “[ Shell Scripting ]” Redirection Operators These operators redirect: standard input (0), standard output (1) and standard error (2). > redirects standard output to a file ps aux > file_name Creates a file and writes standard output. Clobbers any existing file. >> appends standard output to …
This is post 10 of 19 in the series “[ Shell Scripting ]” Any number of commands can be pipelined together. command1 | command2 The above command creates a pipe: the standard output of command1 is connected to the standard input of command2. Any command that can accept Standard Input and produce Standard Output is …