2. Unix Flashcards
T/F Commands are case sensitive
T
Describe the flow of information between functioning units of a computer
- Input accepts info (from user or other machines)
- info passed to memory then the CPU where information is transformed
- Processed output is returned to the user
What are the two main divisions in memory and the Processing unit?
Memory:
- primary/main storage: program storage during execution
- secondary storage
CPU:
- arithmetic logic unit: location of arithmetic & logic operations
- Control unit: controls operation order; accesses, interprets and directs instructions
What are the 3 parts of the unix operating system?
- kernel : control
- shell: interface
- programs: things executed thru shell, via kernel to logic unit
The OS is the suite of programs that make a computer work
What is RAM?
The memory that a computer uses when executing a program
What is the Kernel & what does it do?
Is the control hub of the OS
- allocates time and memory to programs
- Handles the filestore & communications in response to system calls
What is the Shell and what does it do?
Is the interface between the user & kernel
It interprets cmd lines from the user and arranges for their execution. The commands themselves are programs
What previous shells does the bash shell combine?
- bourne shell (sh)
- C shell (csh)
- Korn shell (ksh)
What are some useful features of the Bash shell
- TAB completion
2. History of commands
T/F Everything in UNIZ is either a file or a process
T
What is a process?
an executing program identified by a unique process identifier (PID)
What is a file and give examples
Is a collection of data created by users via text editors, running compliers etc.
ex. script, directory, machine readable file
Describe the process from standard in to out
standard inputs are passed to the program and executed. The processed data is returned through standard out or standard error is something went wrong
What is stream in and out
The process of passing an output as the next input and so on
What is ssh?
A cryptographic network protocol for secure data communication, remote cmd-line login & cmd execution, other secure network services between 2 networked computers
A private key is used to encrypt and decrypt
What does this cmd do:
$scp file1 mhirst@orca1.bcgsc.ca:/home/mhirst/ [enter]
Copies a local file named file1 onto the server and into /home/mhirst dir
mhirst@micb405 /]$ ls [enter]
[mhirst@micb405 /]$ ls -a [enter]
list contents in working dir
-a shows everything including hidden files
what does mkdir do?
Makes a directory
what does “.” and “..” refer to?
”.” current directory (relative path)
“..” parent of the current dir
What does the 10 character string next to a file indicate?
file system security 1. if a dir or not 2 -4: user permissions 5-7: group permissions 8-10: all other permissions
In a file security system was does r, w, x, or - mean?
r: can list files in the dir
w: can delete files in the dir
x: can access files in the fir and read if u have permissions on individual files
- : no permission set
