Commands Reference, Volume 1

ct Command

Purpose

Dials an attached terminal and issues a login process.

Syntax

ct [  -h ] [  -sSpeed ] [  -v ] [  -wNumber ] [  -xNumber ] TelephoneNumber ...

Description

The ct command is a Basic Networking Utilities (BNU) command that enables a user on a remote terminal, such as an 3161, to communicate with a workstation over a telephone line attached to a modem at each end of the connection. The user on the remote terminal can then log in and work on the workstation.

A user on the local system issues the ct command with the appropriate telephone number to call the modem attached to the remote terminal. When the connection is established, the ct command issues a login prompt that is displayed on the remote terminal. The user on the remote terminal enters a login name at the prompt and opens a new shell. The user at the remote terminal then proceeds to work on the workstation just like a local user.

The ct command is useful in the following situations:

• A user working off-site needs to communicate with a local system under strictly supervised conditions, and the local user does not want to disclose the workstation's phone number. Because the local system contacts the remote terminal, the remote user does not need to know the telephone number of the local system. Additionally, the local user issuing the ct command can monitor the work of the remote user.
• The cost of the connection should be charged either to the local site or to a specific account on the calling workstation. If the remote user has the appropriate access permission and can make outgoing calls on the attached modem, that user can make the equivalent of a collect call. The remote user calls the specified local system, logs in, and issues the ct command with the telephone number of the remote terminal, but without the -h flag. The local system hangs up the initial link so that the remote terminal is free for an incoming call and then calls back the modem attached to the remote terminal.

If there are no free lines, the ct command displays a message to that effect and asks if the local user wants to wait for one. If the reply is no, the ct command hangs up. If the local user wants to wait for a free line, the ct command prompts for the number of minutes to wait. The ct command continues to dial the remote system at one-minute intervals until the connection is established or until the specified amount of time has elapsed.

In order to establish a ct connection, the remote user contacts the local user with a regular telephone call and asks the local user to issue the ct command. However, if such connections occur regularly at your site, your system administrator may prefer to set up BNU in such a way that a specified local system automatically issues the ct command to one or more specified terminals at certain designated times.

Notes:

1. Before issuing the ct command, be certain that the remote terminal is attached to a modem that can answer the telephone.
2. If the user issuing the ct command does not have root authority, the port used for the connection must be a shared or delayed port. Otherwise, the remote login will fail. For more information on shared and delayed ports, see the pshare and pdelay commands. In addition, for the ct command to succeed on a shared or delayed port, the user invoking the command must be a member of the UNIX-to-UNIX copy program (uucp) user group.

The ct command is not as flexible as the BNU cu command. For example, the user cannot issue commands on the local system while connected to a remote system through the ct command. However, the ct command does have two features not available with the cu command:

• The user can instruct the ct command to continue dialing the specified telephone number until the connection is established or a set amount of time has elapsed.
• The user can specify more than one telephone number at a time to instruct the ct command to continue dialing each modem until a connection is established over one of the lines.

If the local user specifies alternate dialing paths by entering more than one number on the command line, the ct command tries each line listed in the BNU Devices file(s) (by default, the /etc/uucp/Devices file) until it finds an available line with appropriate attributes or runs out of entries. If there are no free lines, the ct command asks if it should wait for one and, if so, for how many minutes. The ct command continues to try to open the dialers at one-minute intervals until the specified time is exceeded. The local user can override this prompt by specifying a time with the -wNumber flag when entering the command.

After the user logs off, the ct command prompts the user on the remote terminal with a reconnect option; the system can either display a new login prompt or drop the line.

Flags

Examples

1. To dial a modem attached to a remote terminal with an internal telephone number, enter:

   ct 41589

   The internal telephone number of 4-1589 is dialed. The - (hyphen) is optional. The system responds:

   Allocated dialer at 1200 baud
   Confirm hang_up? (y to hang_up)

2. To dial a modem attached to a remote terminal with a local telephone number, enter:
   ct  -w3 9=5553017
   The ct command dials the local telephone number of 555-3017, where dialing 9 is required to reach an outside dial tone. A three-minute wait is specified as the maximum number of minutes that the ct command is to wait for a line.
3. To dial a modem attached to a remote terminal with a long-distance telephone number, enter:
   ct  -w5 9=12345557003
   The command dials the long-distance telephone number of 1-234-555-7003, where 9 is required to reach an outside dial tone. A five-minute wait is specified as the maximum number of minutes that the ct command is to wait for a line.

Files

Related Information

The cu command, pdelay command, pshare command, tip command.