xhost
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The xhost command is a server access control command for the X-window environment.
The command
xhost hostname
adds hostname to the list of clients that can connect to your machine.
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The command xhost + would allow any host to connect to your machine.
This is particularly useful if you need to log in to a remote machine to
perform some task. For example, after logging into some remote host one
can use the setenv command
enable display on the screen of your host.
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The command xhost - hostname removes hostname from
the list of host that can connect to your machine.
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The command xhost - disables access to all client except special
"authorized" clients. These clients would be listed in your .rhosts
file.
talk
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The talk command allows two users on the same host or on different hosts
to have an interactive conversation.
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The talk command divides the window/screen into two parts. The upper part
of the screen/window is the send window while the lower part of the screen/window
is the receive window. Each user is able to type into the send window while
the talk command displays what the other user is typing in the receive
window.
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Using the talk command - some examples:
talk kellyk - talk to a local user
talk dale@wave.com - talk to a remote user
Some notes about using talk:
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The user you wish to talk with must be logged on.
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The "mesg" command can be used to prevent others from "talking" to you.
For example: mesg n
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Talk may be disabled on other systems for security reasons.
See the talk man page for details.
finger
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The finger command displays information about users on a given host. The
host can be either local or remote.
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Example 1: Show who is logged onto the system
finger - show all local logins
finger @wave.com - show remote system's logins
Login Name TTY Idle When Site Info
rjw Robert J West p0 7:11 Sat 10:32
mdine Marc Dine p1 7:11 Wed 09:46
zepht James S. Tallis p2 7:11 Wed 09:46
bqs5 Barbara Baker p3 8:42 Sat 10:33
davek Dave Kiley p4 8:42 Sat 10:33
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Example 2: Show information about a specific user
finger ksmith - look for a local user
finger dale@wave.com - look for a remote user
Login name: dale In real life: Dale Smith
Directory: /u/ibm/dale Shell: /bin/csh
Project:
Parallel Programming for the masses. (Masses of what!)
Plan:
Think globally, act locally: install solar panels !
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If you create a .plan and/or .project file in your home directory and make
them world readable, they will appear in the Plan and Project fields of
the finger output.
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Finger may be disabled on other systems for security reasons.
-
See the finger man page for details.
ping
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The ping command sends an echo request to a network host. It is useful
for:
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Determining the status of the network and various foreign hosts.
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Tracking and isolating hardware and software problems.
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Testing, measuring, and managing networks.
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The ping command sends one datagram per second and prints one line of output
for every response received. Round-trip times and packet loss statistics
are calculated and displayed.
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Example:
% ping farragut
PING farragut.cis.rit.edu: (164.122.27.33): 56 data bytes
64 bytes from 164.122.27.33: icmp_seq=0 ttl=254 time=3 ms
64 bytes from 164.122.27.33: icmp_seq=1 ttl=254 time=2 ms
64 bytes from 164.122.27.33: icmp_seq=2 ttl=254 time=2 ms
64 bytes from 164.122.27.33: icmp_seq=3 ttl=254 time=2 ms
64 bytes from 164.122.27.33: icmp_seq=4 ttl=254 time=2 ms
64 bytes from 164.122.27.33: icmp_seq=5 ttl=254 time=2 ms
^C
----farragut.cis.rit.edu PING Statistics----
6 packets transmitted, 6 packets received, 0% packet loss
round-trip min/avg/max = 2/2/3 ms
See the ping man page for details.
ftp
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ftp stands for File Transfer Protocol. File transfer provides a means for
you to obtain computer files (text, image, sound, etc.) from other computers
over the network.
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ftp can also be used to send (upload) files from your computer to another
computer, providing you have write permission or a real account on the
machine you are uploading.
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The ftp utility has its own set of UNIX like commands which allow you to
perform tasks such as:
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Connect and login to a remote host
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Navigate directories
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List directory contents
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Put and get files
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Transfer files as ascii, ebcdic or binary
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A sample ftp session appears below. The commands which are entered by the
user are in bold type.
farragut% ftp grace.rit.edu
Connected to grace.rit.edu.
220 grace.rit.edu FTP server (Version 4.9 Thu Sep 2 20:35:07 CDT 1993)
Name (grace.rit.edu.edu:jsmith): jsmith
331 Password required for jsmith.
Password:
230 User jsmith logged in.
ftp> dir
200 PORT command successful.
150 Opening data connection for /bin/ls.
total 1464
drwxr-sr-x 3 jsmith staff 1024 Mar 11 20:04 Mail
drwxr-sr-x 2 jsmith staff 1536 Mar 3 18:07 Misc
drwxr-sr-x 5 jsmith staff 512 Dec 7 10:59 OldStuff
drwxr-sr-x 2 jsmith staff 1024 Mar 11 15:24 bin
drwxr-sr-x 5 jsmith staff 3072 Mar 13 16:10 mpl
-rw-r--r-- 1 jsmith staff 209671 Mar 15 10:57 myfile.out
drwxr-sr-x 3 jsmith staff 512 Jan 5 13:32 public
drwxr-sr-x 3 jsmith staff 512 Feb 10 10:17 pvm3
226 Transfer complete.
ftp> cd mpl
250 CWD command successful.
ftp> dir
200 PORT command successful.
150 Opening data connection for /bin/ls.
total 7320
-rw-r--r-- 1 jsmith staff 1630 Aug 8 1994 dboard.f
-rw-r----- 1 jsmith staff 4340 Jul 17 1994 vttest.c
-rwxr-xr-x 1 jsmith staff 525574 Feb 15 11:52 wave_shift
-rw-r--r-- 1 jsmith staff 1648 Aug 5 1994 wide.list
-rwxr-xr-x 1 jsmith staff 4019 Feb 14 16:26 fix.c
226 Transfer complete.
ftp> get wave_shift
200 PORT command successful.
150 Opening data connection for wave_shift (525574 bytes).
226 Transfer complete.
528454 bytes received in 1.296 seconds (398.1 Kbytes/s)
ftp> quit
221 Goodbye.
Many computers on the Internet permit anonymous ftp . You can login
to these machines without a real account, to obtain files which have been
made publicly available. Typically, the user name anonymous is
used, coupled with your email address as the password.
Anonymous ftp is usually restricted so that users can only see what the
server permits them to see. Anonymous users do not have full privileges
as would a user with a real computer account.
See the ftp man page for details.
telnet
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Telnet is a utility that allows a computer user at one site to make a connection,
login and then conduct work on a computer at another site. For example,
you can use the telnet command to run a program in your directory on a
supercomputer thousands of miles away.
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Telnet is used to access many of the Internet resources, such as databases,
libraries and computers
-
Example telnet session:
% telnet grace
Trying...
Connected to grace.rit.edu.
Escape character is '^]'.
Digital UNIX (grace) (ttyp1)
login: jsmith
Password:
Last login: Wed Oct 8 01:51:36 from yorktown.cis.rit
Digital UNIX V3.2D-1 (Rev. 41); Fri Oct 25 20:21:47 EDT 1996
Digital UNIX V3.2D-1 Worksystem Software (Rev. 41)
Please contact the ISC HelpDesk at 475-6929 voice or 475-2810 tty,
stop by our office in Ross room A291, or use ASK Information
Systems and Computing for questions or concerns.
***************************************************************************
You have mail.
Disk quotas for user 8350 (uid 8350):
Filesystem blocks quota limit grace files quota limit grace
/users 762 6400 6400 53 6400 6400
{ do some work }
% logout
Connection closed by foreign host.
See the telnet man page for details.
rlogin
rsh
rcp
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rlogin (remote login), rsh (remote shell) and rcp (remote copy) are three
utilities which allow you to perform tasks on other machines without requiring
the usual login authentication.
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All three utilities depend upon a .rhosts located in your home directory.
The .rhosts file contains the names of your "trusted" hosts and your userid
on each of those hosts. An example appears below:
apache.unm.edu jsmith
zeus.mit.edu jsmith
athena.com smith
fox.eeco.org smithj
rlogin: Allows you to login to a remote machine. It is nearly identical
to telnet in function and appearance, however if your .rhosts file is setup
accordingly, you will be able to login to your account on another machine
wihout having to enter a userid and password.
rsh: The remote shell command can be used to execute a command on remote
host or log into remote host. With the proper .rhosts file, authentication
is not required.
Examples:
rsh host2 - will connect to host2 for
login
rsh host2 df - check the amount of free
disk space on remote host2
rsh host2 ps aux |grep jsmith - check for processes owned
by jsmith on host2
rsh host2 rm /tmp/myfile.old - remove a file in host2
rsh host2 cat test1 ">>" test2 - append test1 file on remote
host to test2 file on remote
host
rsh host2 cat test1 >> test2 - append test1 file on remote
host to test2 file on local
host
rcp: Remote copy enables you to copy files between different systems. With
the proper .rhosts file, authentication is not required.
Example:
rcp localfile host2:/home/eng/journal
See the following man pages for details:
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