Linux Notes

An operating system that can run on many different machines is said to be portable.

Like other operating systems, the UNIX system is a control program for computers.

Can support many users.

A file is a collection of information.

Shell commands can be arranged in a file for later execution as a high-level program.

Devices (such as a printer or terminal ) and disk files all appear as files to UNIX programs.  Under the UNIX operating system, input and output are device-independent.

A pipe sends the output of one program to another program as input. A filter is a program designed to process a stream of input data and yield a stream of output data.
// running linux
9/17/09
bash is the most commonly used and most powerful shell on Linux.

echo $SHELL

^U delete the whole line.

noclobber=1 # prevent overwriting with >

make all files under a folder readable to everyone:
landshark-clued0:/d0mino> chmod +r weigang -R

9/26/09
export PATH=$PATH:/usr/sbin

cd is a builtin command.

$ apropos edit will simply print out all the NAME lines that contain the string you ask for.

read permission means you can look at the file's contents.
write permission means you can change or delete the file.
execute permission means you can run the file as a program.

for a directory:

read permission means you can list the contents of that directory.
write permission means you can add or remove files in that directory.
execute permission means you can list information about the files in that directory.

read permission means you can look at the file's contents.
write permission means you can change or delete the file.
execute permission means you can run the file as a program.

3 permissions: read, write, execute.
3 levels: owner, group, other.

on unix, the finite resources of the system, like the memory and the disks, are managed by one all-powerful program called the kernel. everything else on the system is called a process.