This is the sequence of events when you are creating a new user. Use the sudo adduser jsmith command to add a new user named jsmith. After that, you can type other information to identify your user and then set a password to secure their account.
jason@Yog-Sothoth:~$ sudo adduser jsmith Adding user `jsmith' ... Adding new group `jsmith' (1001) ... Adding new user `jsmith' (1001) with group `jsmith' ... Creating home directory `/home/jsmith' ... Copying files from `/etc/skel' ... Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully Changing the user information for jsmith Enter the new value, or press ENTER for the default Full Name []: John Smith Room Number []: 101 Work Phone []: 09 677 677 677 Home Phone []: 09 123 123 123 Other []: Is the information correct? [Y/n] Y |
Then you can type this command using the finger(1) command to verify that this user does exist.
jason@Yog-Sothoth:~$ finger jsmith Login: jsmith Name: John Smith Directory: /home/jsmith Shell: /bin/bash Office: 101, 09 677 677 677 Home Phone: 09 123 123 123 Never logged in. No mail. No Plan. |
The users command will be very useful on a Linux system; you can type this to list all logged in users.
jason@Yog-Sothoth:~$ users jason |
If you have defined an alias in your bash shell and you want to get rid of it you can use the unalias command to remove the alias so that you can redefine it or just get it out of the way. Below is an example of the usage.
jason@Yog-Sothoth:~$ unalias la |
Then you can create a new alias in place of the old one. Just use the alias command to create a new alias containing whatever you wish.
jason@Yog-Sothoth:~$ alias la="ls -la" |
This is the output of the nstat command that will print information about your network connection.
jason@Yog-Sothoth:~$ nstat #kernel IpInReceives 1269 0.0 IpInAddrErrors 2 0.0 IpInDelivers 1233 0.0 IpOutRequests 1284 0.0 IpOutDiscards 32 0.0 IcmpInErrors 32 0.0 IcmpInTimeExcds 32 0.0 IcmpOutErrors 32 0.0 IcmpOutTimeExcds 32 0.0 IcmpMsgInType3 32 0.0 IcmpMsgOutType3 32 0.0 TcpActiveOpens 80 0.0 TcpEstabResets 1 0.0 TcpInSegs 904 0.0 TcpOutSegs 952 0.0 TcpOutRsts 10 0.0 UdpInDatagrams 262 0.0 UdpNoPorts 32 0.0 UdpOutDatagrams 296 0.0 Ip6InReceives 9 0.0 Ip6InDelivers 8 0.0 Ip6OutRequests 18 0.0 Ip6OutNoRoutes 4 0.0 Ip6InMcastPkts 9 0.0 Ip6OutMcastPkts 24 0.0 Ip6InOctets 2808 0.0 Ip6OutOctets 3419 0.0 Ip6InMcastOctets 2808 0.0 Ip6OutMcastOctets 3895 0.0 Icmp6OutMsgs 10 0.0 Icmp6OutRouterSolicits 3 0.0 Icmp6OutNeighborSolicits 1 0.0 Icmp6OutMLDv2Reports 6 0.0 Icmp6OutType133 3 0.0 Icmp6OutType135 1 0.0 Icmp6OutType143 6 0.0 Udp6InDatagrams 7 0.0 Udp6OutDatagrams 8 0.0 TcpExtPruneCalled 1 0.0 TcpExtTW 37 0.0 TcpExtDelayedACKs 25 0.0 TcpExtDelayedACKLost 15 0.0 TcpExtTCPHPHits 389 0.0 TcpExtTCPPureAcks 103 0.0 TcpExtTCPHPAcks 35 0.0 TcpExtTCPRcvCollapsed 11 0.0 TcpExtTCPDSACKOldSent 15 0.0 TcpExtTCPAbortOnData 2 0.0 TcpExtTCPAbortOnClose 1 0.0 IpExtInMcastPkts 16 0.0 IpExtOutMcastPkts 20 0.0 IpExtInBcastPkts 2 0.0 IpExtInOctets 714373 0.0 IpExtOutOctets 180638 0.0 IpExtInMcastOctets 3637 0.0 IpExtOutMcastOctets 3797 0.0 IpExtInBcastOctets 656 0.0 |
The lnstat command will also print information about your network connection. This example will print information about your arp tables.
jason@Yog-Sothoth:~$ lnstat -k arp_cache:entries,rt_cache:in_hit,arp_cache:destroys arp_cach|rt_cache|arp_cach| entries| in_hit|destroys| 1| 2217| 3| |
This lnstat command will print out a lot of information about your network connection; this is hard to read though.
jason@Yog-Sothoth:~$ lnstat -i 10 arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|arp_cach|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|rt_cache|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca|ndisc_ca| entries| allocs|destroys|hash_gro| lookups| hits|res_fail|rcv_prob|rcv_prob|periodic|forced_g|unresolv| entries| in_hit|in_slow_|in_slow_|in_no_ro| in_brd|in_marti|in_marti| out_hit|out_slow|out_slow|gc_total|gc_ignor|gc_goal_|gc_dst_o|in_hlist|out_hlis| entries| allocs|destroys|hash_gro| lookups| hits|res_fail|rcv_prob|rcv_prob|periodic|forced_g|unresolv| | | | ws| | | ed|es_mcast|es_ucast|_gc_runs| c_runs|ed_disca| | | tot| mc| ute| | an_dst| an_src| | _tot| _mc| | ed| miss| verflow| _search|t_search| | | | ws| | | ed|es_mcast|es_ucast|_gc_runs| c_runs|ed_disca| | | | | | | | | | | | rds| | | | | | | | | | | | | | | | | | | | | | | | | | | | | rds| 1| 0| 0| 0| 17| 17| 0| 0| 0| 37| 0| 0| 114| 447| 11| 0| 0| 0| 0| 0| 246| 58| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 0| 3| 1| 0| 0| 0| 37| 0| 0| |
Use the route command to show information about your kernel IP routing table.
jason@Yog-Sothoth:~$ sudo route [sudo] password for john: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default 192.168.1.1 0.0.0.0 UG 0 0 0 wlan0 192.168.1.0 * 255.255.255.0 U 0 0 0 wlan0 |
Use the sudo arp command to show information about the Internet to Ethernet translation tables used for your network. In my case I am connected via WIFI, so the output is a little different.
jason@Yog-Sothoth:~$ sudo arp 192.168.1.1 ? (192.168.1.1) at c8:14:51:5f:a9:47 on en0 ifscope [ethernet] |
use the dig command to return information about a hostname. This is just like the nslookup command, but provides more control over the query creation.
jason@Yog-Sothoth:~$ dig yahoo.com ; <<>> DiG 9.8.3-P1 <<>> yahoo.com ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53451 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;yahoo.com. IN A ;; ANSWER SECTION: yahoo.com. 238 IN A 98.139.180.180 yahoo.com. 238 IN A 98.138.252.38 yahoo.com. 238 IN A 206.190.39.42 ;; Query time: 29 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Tue Jan 2 13:50:31 2018 ;; MSG SIZE rcvd: 75 |