Introduction to Linux in HPC/Various tips

Video

Linux Introduction Slides 130 - 136 (7 pages)

Slide Layout

   page 1: 
       Please make backups regularly!
   page 2: 
       du command
       df command
   page 3: 
       history command
       the ~/.bash_history file
   page 4: 
       ln command and syntax
   page 5: 
       watch command and the usage
   page 6: 
       $(( )) as integer calculator
   page 7: 60 sec
       very brief into to sed
       just mention awk

Quiz

How will you find a specific command in history ? HINT: use grep with history, how to use it?

Click and submit to see the answer

How can you compare two files and display a list of the difference? HINT: man diff

Click and submit to see the answer

Info:

Please make backups regularly!

Warning:

Please make backups regularly!

Exercises in Terminal (slide 137)

1. Find out the number of CPUs and amount of memory you have.

Answer:

     There are multiple ways to find out the number of CPUs and amount of memory on Linux computer. 
     the number of CPUs.
      1. lscpu: the following is an example output of the  lscpu command:

        CPU(s):                40
        On-line CPU(s) list:   0-39

     Brief description:
           CPU(s):                40: this computer contains 40 CPU cores.
           On-line CPU(s) list:   0-39: all 40 CPU cores are active.
      2. grep -c processor /proc/cpuinfo: This command uses  grep to count the number of lines that match  processor in  /proc/cpuinfo. The following is an example output:

        $ grep -c processor /proc/cpuinfo
        40

     As can be seen, there are 40 CPU cores in this computer.
     the amount of memory
      1. vmstat -s: the following is an example output of the vmstat command:

           196698736 K total memory
           4982596 K used memory

        vmstat reports the virtual memory statistics.
        The -s option displays a table for memory statistics.
        In this example there are 196 GB memory in total in the computer and 5 GB memory is used.
      2. grep Mem[TF] /proc/meminfo: This command uses grep to search for either MemT or MemF in /proc/meminfo and the following is an example output:

           $ grep Mem[TF] /proc/meminfo
           MemTotal:       196698740 kB
           MemFree:        113479460 kB

         As can be seen, MemT and MemF are matched by MemTotal and MemFree, respectively. The total amount of memory in the computer is 196 GB and there are 113 GB are freely available.

2. Permanently change your vim color scheme. 

Answer:

     Your personal vim configuration file is ~/.vimrc. In this file you can change the vim color scheme permanently. For example, the following setting uses the desert color scheme:
      colorscheme desert
     But beware of this permanent change of vim color scheme, because different color schemes may be preferred by different people. The vim color scheme recommended by others may not be the best choice for you.