lscpu

list of cpus.

lsmem

list of memory.

lsof (list open files)

lsof -i tcp:80

df (disk free space)

Display free disk space  

Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1       32G  4.7G   26G  16% /
tmpfs           1.9G     0  1.9G   0% /dev/shm

du (disk space usage)

 du - estimate file space usage
 du -sh /var/*

id

$ id
uid=501(operations) gid=100(users) groups=100(users)

curl

curl -I -s google.com

-I : Header information.
-s : silence body response.
-k : insecure
-v : verbose
-V : version

ps

$ ps -ef 
$ ps -u <username> (display all user processes)
$ sudo ps aux
a = show processes for all users
u = display the process's user/owner
x = also show processes not attached to a terminal

docker stats

$ docker stats <container-id>
CONTAINER ID        NAME                CPU %               MEM USAGE / LIMIT     MEM %               NET I/O             BLOCK I/O           PIDS
5e1485ac499f        zen_khayyam         0.17%               147.5MiB / 9.251GiB   1.56%               14.3MB / 18.4MB     113MB / 8.66MB      64

basic comamnds

> cat, ls, tail, env

chmod

chmod 400 shh_key.pem

history (display history commands)

$ history 
   63  kubectl describe pv pvc-b3123e13-51e3-11e9-b709-124cac572d38 
   64  kubectl delete pv pvc-b3123e13-51e3-11e9-b709-124cac572d38 
   65  clear
   66  kubectl get pods
   67  kubectl get pods
   68  clear
   69  kubectl get pods
   70  kubectl get pods
   71  kubectl get ns
   72  kubectl get pod