# Minute       Hour          Day of Month       Month                         Day of Week        Command  
# (0-59)        (0-23)                 (1-31)           (1-12 or Jan-Dec)       (0-6 or Sun-Sat)              

string         meaning
------         -------
@reboot        Run once, at startup.
@yearly        Run once a year, "0 0 1 1 *".
@annually      (same as @yearly)
@monthly       Run once a month, "0 0 1 * *".
@weekly        Run once a week, "0 0 * * 0".
@daily         Run once a day, "0 0 * * *".
@midnight      (same as @daily)
@hourly        Run once an hour, "0 * * * *".

https://www.pantz.org/software/cron/croninfo.html

in chrome ,

how to navigate foward : CTRL+tab
how to navigate backward : CTRL+SHIFT+TAB


CPU and memory info from the files /proc/cpuinfo and /proc/meminfo, utilisation from commands such as sar, vmstat, etc. Please look at those.


-sh-4.1$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                8
On-line CPU(s) list:   0-7
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             8
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 45
Stepping:              7
CPU MHz:               2700.000
BogoMIPS:              5400.00
Hypervisor vendor:     VMware
Virtualization type:   full
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              20480K
NUMA node0 CPU(s):     0-7
-sh-4.1$

========================================
-sh-4.1$ cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70GHz
stepping        : 7
cpu MHz         : 2700.000
cache size      : 20480 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 x2apic popcnt aes xsave avx hypervisor lahf_lm ida arat epb xsaveopt pln pts dts
bogomips        : 5400.00
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70GHz
stepping        : 7
cpu MHz         : 2700.000
cache size      : 20480 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 x2apic popcnt aes xsave avx hypervisor lahf_lm ida arat epb xsaveopt pln pts dts
bogomips        : 5400.00
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management:

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70GHz
stepping        : 7
cpu MHz         : 2700.000
cache size      : 20480 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 x2apic popcnt aes xsave avx hypervisor lahf_lm ida arat epb xsaveopt pln pts dts
bogomips        : 5400.00
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management:
=========================================================

Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70GHz -->  it means you are having Intel cpu having speed of 2 giga hurtz

if you get ouput has

-sh-4.1$ cat /proc/cpuinfo | grep processor
processor       : 0
processor       : 1
processor       : 2
processor       : 3
processor       : 4
processor       : 5
processor       : 6
processor       : 7

and no of core = 2 

then , it means you have 4 physical processor and each having 2 cores. 

No of cores represents multi threading means each processor can accept 2 tasks at a time.

CPU is a processing unit and it has number of processor. or you can say processor and cpu are both same.

if a processor or CPU has 4 core , then it means it quad core processor.


ps aux | awk '{print $2, $4, $11}' | sort -k2rn | head -n 20


This will list the first 20 applications in reverse order, from the one using more RAM to the one using lest RAM

==============================================

-sh-4.1$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                8
On-line CPU(s) list:   0-7
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             8
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 45
Stepping:              7
CPU MHz:               2700.000
BogoMIPS:              5400.00
Hypervisor vendor:     VMware
Virtualization type:   full
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              20480K
NUMA node0 CPU(s):     0-7
-sh-4.1$

=========================

ctrl+alt+end to chnage the password of remote desktop.

====================

Loopback address is a special IP number (127.0.0.1) that is designated for the software loopback interface of a machine. ... The loopback interface allows IT professionals to test IP software without worrying about broken or corrupted drivers or hardware.