Learn Basic Linux-Command | PART 2

Arief-jr.blogspot.com - In previously post have been discussed about Learn Basic Linux-command | PART 1, now i will explain sequel.

File Descriptor

 

1. Output to monitor (standard output), input from system (kernel)

$ ps

2. Output to monitor (standard output), input from keyboard (input standard)

$ cat hello, what's up!!! hello, what's up!!! exit with ^d [ctrl+d]

3. Input from keyboard and output to internet address

$ mail arief-jr@gmail.com

4. Input name directory, nothin output (create new directory), if an error then error display on screen (screen standard)

$ mkdir [dir name] $ mkdir mydir (there error message, because this directory already created)

Redirection

1. Output standard redirect

$ cat 1> filename.txt this is a text created by me


2. Notation 2>&1: Error standard redirection (2>) is identical with file descriptor 1.
   

   $ ls newfile (there error message)
   $ ls newfile 2> result.txt
   $ cat result.txt
   $ ls newfile 2> result.txt 2>&1
   $ cat result.txt

   
   
3. For standard output redirection to file, use operator >

$ echo hello

$ echo helllo > output

$ cat output

4. Input standard redirect and output standard can combined but do not us sama file name as input standard or output

$ cat < output > out

$ cat out

$ cat < output >> out

$ cat out

$ cat < output > output

$ cat outpit

$ cat < out >> out (process won't stop)

$ cat out

Pipeline

• Pipeline operator ( | ) used for make process execute by passing data driectly to other data

$ who

$ who | sort

$ who | sort -r

$ who > tmp

$ sort tmp

$ rm tmp

$ ls -l /etc | more

$ ls -l /etc | sort | more

Filter

• Pipeline also used for combines the utility system to form more complex functions

$ w -h | grep

$ greo user /etc/passwd

$ ls /etc | wc

$ ls /etc | wc -l

Maybe that my explain about Linux-Command. So if you want learning, please. Because learning not need younger, smart or experience and other the most important we still understand.

"There is a will there is a way"

There may be suggestions or ideas that you want to add or also sharing ? please add and contact me via Google+  


Thanks, may be useful and good luck!!! Arief