====== Cisco manual ======
 

( https://www.samuraj-cz.com/clanek/cisco-ios-1-uvod-prikaz-show/ ):

( print every show commands ) 
<code bash>
sh ?
</code>
( show running config )
<code bash>
sh run
</code>
( show interface description )
<code bash>
show int des
</code> 
( show ip interfaces brief )
<code bash>
sh ip int br
</code>
( show logging )
<code bash>
sh log
</code>

To changing coniguration: 
<code bash>
conf t
</code> ( configure terminal, to return Ctr + z )
Example change some interface:
<code bash>
int Gi2/0/14
</code> ( some interface from show int des )
Before change print configuration interface :
<code bash>
Mainswitch#sh run int Gi2/0/14
Building configuration...

Current configuration : 318 bytes
!
interface GigabitEthernet2/0/14
 description BC10 Huawei MM2
 switchport access vlan 247
 switchport mode access
 no logging event link-status
 no snmp trap link-status
 storm-control broadcast level pps 200 150
 storm-control multicast level pps 100 80
 spanning-tree portfast
 spanning-tree bpduguard disable
end
</code>

After that for example change VLAN :

<code bash>
conf t
</code> ( enter configuration mode )
<code bash>
int Gi2/0/14
</code> ( enter configuratio interface )
<code bash>
switchport access vlan 240
</code> ( change VLAN access )
To change VLAN access to trunk
<code bash>
no  switchport access vlan 247
</code> ( delete access mode conf ) 
<code bash>
no  switchport mode access
</code>     ( delete access mode conf ) 
<code bash>
switchport mode trunk
</code>
Save configuration :
<code bash>
write
</code> ( save configuration )