- Finding Feature Information
- Prerequisites for Cisco IOS Scripting with Tcl
- Restrictions for Cisco IOS Scripting with Tcl
- Information About Cisco IOS Scripting with Tcl
- How to Configure Cisco IOS Scripting with Tcl
- Configuration Examples for Cisco IOS Scripting with Tcl
- Additional References
- Feature Information for Cisco IOS Scripting with Tcl
- Glossary
Cisco IOS Scripting with Tcl
The Cisco IOS Scripting with Tcl feature provides the ability to run Tool Command Language (Tcl) version 8.3.4 commands from the Cisco IOS command-line interface (CLI).
- Finding Feature Information
- Prerequisites for Cisco IOS Scripting with Tcl
- Restrictions for Cisco IOS Scripting with Tcl
- Information About Cisco IOS Scripting with Tcl
- How to Configure Cisco IOS Scripting with Tcl
- Configuration Examples for Cisco IOS Scripting with Tcl
- Additional References
- Feature Information for Cisco IOS Scripting with Tcl
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Cisco IOS Scripting with Tcl
- Familiarity with Tcl programming and Cisco IOS commands is required.
- Tcl commands can be executed from the Tcl configuration mode using the Cisco IOS CLI. Tcl configuration mode is accessed from privileged EXEC mode. Access to privileged EXEC mode should be managed by restricting access using the enable command password.
Restrictions for Cisco IOS Scripting with Tcl
- If Cisco IOS configuration commands are used within the Tcl scripts, submode commands must be entered as quoted arguments on the same line as the configuration command.
- Error messages are provided, but you must check that the Tcl script will run successfully because errors may cause the Tcl shell to run in an infinite loop.
Caution |
The use of Tcl server sockets to listen to telnet and FTP ports (23 and 21 respectively) will preempt the normal handling of these ports in Cisco IOS software. |
- The table below lists Tcl commands and library calls that do not behave within Cisco IOS software as documented in standard Tcl documents.
Table 1 | Tcl Command Options That Behave Differently in Cisco IOS Software |
Command |
Keyword |
Argument |
Supported |
Comments |
---|---|---|---|---|
after |
ms |
script |
Partially |
When the CLI tclsh command is used, there is no event loop implemented unless Embedded Syslog Manager (ESM) is active on the same router. Commands entered using the after Tcl command will not run unless forced using the update command. Sleep mode (the after command) works only with the ms keyword. |
file |
-time |
atime |
No |
The optional -time keyword to set the file access time is not supported in Cisco IOS software. |
file |
-time |
mtime |
No |
The optional -time keyword to set the file modification time is not supported in Cisco IOS software. |
fileevent |
|
|
Partially |
When the CLI tclsh command is used, there is no event loop implemented unless Embedded Syslog Manager (ESM) is active on the same router. Commands entered using the fileevent Tcl command will not run unless forced using the update command. |
history |
! n |
|
Partially |
The ! n shortcut does not work in Cisco IOS software. Use the history Tcl command with the redo n keyword. |
load |
|
|
No |
When the CLI load command is used, an error message stating "dynamic loading not available on this system" is displayed. |
Information About Cisco IOS Scripting with Tcl
- Tcl Shell for Cisco IOS Software
- Tcl Precompiler
- SNMP MIB Object Access
- Custom Extensions in the Tcl Shell
- SNMP MIB Custom Extensions in the Tcl Shell
Tcl Shell for Cisco IOS Software
The Cisco IOS Tcl shell was designed to allow customers to run Tcl commands directly from the Cisco IOS CLI prompt. Cisco IOS software does contain some subsystems such as Embedded Syslog Manager (ESM) and Interactive Voice Response (IVR) that use Tcl interpreters as part of their implementation. These subsystems have their own proprietary commands and keyword options that are not available in the Tcl shell.
Several methods have been developed for creating and running Tcl scripts within Cisco IOS software. A Tcl shell can be enabled, and Tcl commands can be entered line by line. After Tcl commands are entered, they are sent to a Tcl interpreter. If the commands are recognized as valid Tcl commands, the commands are executed and the results are sent to the TTY device. If a command is not a recognized Tcl command, it is sent to the Cisco IOS CLI parser. If the command is not a Tcl or Cisco IOS command, two error messages are displayed. A predefined Tcl script can be created outside of Cisco IOS software, transferred to flash or disk memory, and run within Cisco IOS software. It is also possible to create a Tcl script and precompile the code before running it under Cisco IOS software.
Multiple users on the same router can be in Tcl configuration mode at the same time without interference because each Tcl shell session launches a separate interpreter and Tcl server process. The TTY interface number served by each Tcl process is represented in the server process name and can be displayed using the show process CLI command.
The Tcl shell can be used to run Cisco IOS CLI EXEC commands within a Tcl script. Using the Tcl shell to run CLI commands allows customers to build menus to guide novice users through tasks, to automate repetitive tasks, and to create custom output for show commands.
Tcl Precompiler
The Cisco IOS Tcl implementation offers support for loading scripts that have been precompiled by the TclPro precompiler. Precompiled scripts allow a measure of security and consistency because they are obfuscated.
SNMP MIB Object Access
Designed to make access to Simple Network Management Protocol (SNMP) MIB objects easier, a set of UNIX-like SNMP commands has been created. The Tcl shell is enabled either manually or by using a Tcl script, and the new commands can be entered to allow you to perform specified get and set actions on MIB objects. To increase usability, the new commands have names similar to those used for UNIX SNMP access. To access the SNMP commands go to, Using the Tcl Shell to Access SNMP MIB Objects.
Custom Extensions in the Tcl Shell
The Cisco IOS implementation of the Tcl shell contains some custom command extensions. These extensions operate only under Tcl configuration mode. The table below displays these command extensions.
Table 2 | Cisco IOS Custom Tcl Command Extensions |
Command |
Description |
---|---|
fconfigure -remote [host port] -broadcast boolean vrf[vrf_table_name] |
Specifies the options in a channel and enables you to associate a virtual routing and forwarding (VRF) table name with it. |
ios_config |
Runs a Cisco IOS CLI configuration command. |
log_user |
Toggles Tcl command output under Tcl configuration mode. |
socket -myvrf [vrf_table_name] |
Opens a TCP network connection and enables you to associate a VRF table name with it. |
typeahead |
Writes text to the router standard input (stdin) buffer file. |
tclquit |
Leaves Tcl shell--synonym for exit. |
udp_open -ipv6 port |
Opens a User Datagram Protocol (UDP) socket. |
udp_peek sock -buffersize buffer-size |
Enables peeking into a UDP socket. |
SNMP MIB Custom Extensions in the Tcl Shell
The Cisco IOS implementation of the Tcl shell contains some custom command extensions for SNMP MIB object access. These extensions operate only under Tcl configuration mode. The table below displays these command extensions.
Table 3 | Cisco IOS Custom Tcl Command Extensions for SNMP MIB Access |
How to Configure Cisco IOS Scripting with Tcl
- Enabling the Tcl Shell and Using the CLI to Enter Commands
- Using the Tcl Shell to Access SNMP MIB Objects
- Running Predefined Tcl Scripts
Enabling the Tcl Shell and Using the CLI to Enter Commands
Perform this task to enable the interactive Tcl shell and to enter Tcl commands line by line through the Cisco IOS CLI prompt. Optional steps include specifying a default location for encoding files and specifying an initialization script.
DETAILED STEPS
Examples
The following sample (partial) output shows information about Ethernet interface 0 on the router. The show interfaces command has been executed from Tcl configuration mode.
Router# tclsh Router(tcl)# exec "show interfaces" Ethernet 0 is up, line protocol is up Hardware is MCI Ethernet, address is 0000.0c00.750c (bia 0000.0c00.750c) Internet address is 10.108.28.8, subnet mask is 255.255.255.0 MTU 1500 bytes, BW 10000 Kbit, DLY 100000 usec, rely 255/255, load 1/255 Encapsulation ARPA, loopback not set, keepalive set (10 sec) ARP type: ARPA, ARP Timeout 4:00:00 Last input 0:00:00, output 0:00:00, output hang never Last clearing of "show interface" counters 0:00:00 Output queue 0/40, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec Five minute output rate 2000 bits/sec, 4 packets/sec 1127576 packets input, 447251251 bytes, 0 no buffer Received 354125 broadcasts, 0 runts, 0 giants, 57186* throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 5332142 packets output, 496316039 bytes, 0 underruns 0 output errors, 432 collisions, 0 interface resets, 0 restarts . . .
Troubleshooting Tips
Use the Tcl puts command in a Tcl script to trace command execution.
Using the Tcl Shell to Access SNMP MIB Objects
Perform this task to enable the interactive Tcl shell and enter Tcl commands to perform actions on MIB objects.
The SNMP community configuration must exist in the running configuration of the router.
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
|
Example: Router> enable |
Enables privileged EXEC mode.
|
|
Example: Router# configure terminal |
(Optional) Enters global configuration mode. |
|
Example: Router(config)# scripting tcl encdir tftp://10.18.117.23/enctcl/ |
(Optional) Specifies the default location of external encoding files used by the Tcl encoding command. |
|
Example: Router(config)# scripting tcl init ftp://user:password@172.17.40.3/tclscript/initfiles3.tcl |
(Optional) Specifies an initialization script to run when the Tcl shell is enabled. |
|
Example: Router(config)# exit |
(Optional) Exits global configuration mode and returns to privileged EXEC mode. |
|
Example: Router# tclsh |
Enables the interactive Tcl shell and enters Tcl configuration mode. |
|
Example: Router(tcl)# proc get_bri {} |
Commands entered in Tcl configuration mode are sent first to the interactive Tcl interpreter. If the command is not a valid Tcl command, it is sent to the CLI parser. |
|
Example: Router(tcl)# snmp_getbulk public 1 3 1.3.6.1.2.1.1.1 1.3.6.1.2.1.10.18.8.1.1 |
(Optional) Retrieves a large section of a MIB table.
|
|
Example: Router(tcl)# snmp_getid private |
(Optional) Retrieves the following variables from the SNMP entity on the router: sysDesrc.0, sysObjectID.0, sysUpTime.0, sysContact.0, sysName.0, and sysLocation.0.
|
|
Example: Router(tcl)# snmp_getnext public 1.3.6.1.2.1.1.1.0 1.3.6.1.2.1.1.2.0 |
(Optional) Retrieves a set of individual variables from a MIB table.
|
|
Example: Router(tcl)# snmp_getone public 1.3.6.1.2.1.1.1.0 1.3.6.1.2.1.1.2.0 |
(Optional) Retrieves a set of individual variables from a MIB table.
|
|
Example: Router(tcl)# snmp_setany private 1.3.6.1.2.1.1.5.0 -d TCL-SNMP_TEST |
(Optional) Retrieves current values of specified variables from a MIB table and then performs a set request on the variables.
|
|
Example: Router(tcl)# exit |
Exits Tcl configuration mode and returns to privileged EXEC mode. |
Troubleshooting Tips
Use the Tcl puts command in a Tcl script to trace command execution.
Running Predefined Tcl Scripts
Perform this optional task to run a predefined Tcl script in Cisco IOS software.
Before performing this task, you must create a Tcl script that can run on Cisco IOS software. The Tcl script may be transferred to internal flash memory using any file system that the Cisco IOS file system (IFS) supports, including TFTP, FTP, and rcp. The Tcl script may also be sourced from a remote location.
DETAILED STEPS
Command or Action | Purpose | |
---|---|---|
|
Example: Router> enable |
Enables privileged EXEC mode.
|
|
Example: Router# tclsh |
Enables the interactive Tcl shell and enters Tcl configuration mode. |
|
Example: Router(tcl)# source slot0:test.tcl |
Commands entered in Tcl configuration mode are sent first to the interactive Tcl interpreter. If the command is not a valid Tcl command, it is then sent to the CLI parser. |
|
Example: Router(tcl)# exit |
Exits Tcl configuration mode and returns to privileged EXEC mode. |
Configuration Examples for Cisco IOS Scripting with Tcl
- Example Tcl Script Using the show interfaces Command
- Example Tcl Script for SMTP Support
- Example Tcl Script for SNMP MIB Access
Example Tcl Script Using the show interfaces Command
Using the Tcl regular expression engine, scripts can filter specific information from show commands and present it in a custom format. The following is an example of filtering the show interfaces command output and creating a comma-separated list of BRI interfaces on the router:
tclsh proc get_bri {} { set check "" set int_out [exec "show interfaces"] foreach int [regexp -all -line -inline "(^BRI\[0-9]/\[0-9])" $int_out] { if {![string equal $check $int]} { if {[info exists bri_out]} { append bri_out "," $int } else { set bri_out $int } set check $int } } return $bri_out }
Example Tcl Script for SMTP Support
The following Tcl script is useful for sending e-mail messages from a router.
## ## Place required comments here!!! ## package provide sendmail 2.0 # Sendmail procedure for Support namespace eval ::sendmail { namespace export initialize configure sendmessage sendfile array set ::sendmail::sendmail { smtphost mailhub from "" friendly "" } proc configure {} {} proc initialize {smtphost from friendly} { variable sendmail if {[string length $smtphost]} then { set sendmail(smtphost) $smtphost } if {[string length $from]} then { set sendmail(from) $from } if {[string length $friendly]} then { set sendmail(friendly) $friendly } } proc sendmessage {toList subject body {tcl_trace 0}} { variable sendmail set smtphost $sendmail(smtphost) set from $sendmail(from) set friendly $sendmail(friendly) if {$trace} then { puts stdout "Connecting to $smtphost:25" } set sockid [socket $smtphost 25] ## DEBUG set status [catch { puts $sockid "HELO $smtphost" flush $sockid set result [gets $sockid] if {$trace} then { puts stdout "HELO $smtphost\n\t$result" } puts $sockid "MAIL From:<$from>" flush $sockid set result [gets $sockid] if {$trace} then { puts stdout "MAIL From:<$from>\n\t$result" } foreach to $toList { puts $sockid "RCPT To:<$to>" flush $sockid } set result [gets $sockid] if {$trace} then { puts stdout "RCPT To:<$to>\n\t$result" } puts $sockid "DATA " flush $sockid set result [gets $sockid] if {$trace} then { puts stdout "DATA \n\t$result" } puts $sockid "From: $friendly <$from>" foreach to $toList { puts $sockid "To:<$to>" } puts $sockid "Subject: $subject" puts $sockid "\n" foreach line [split $body "\n"] { puts $sockid " $line" } puts $sockid "." puts $sockid "QUIT" flush $sockid set result [gets $sockid] if {$trace} then { puts stdout "QUIT\n\t$result" } } result] catch {close $sockid } if {$status} then { return -code error $result } return } proc sendfile {toList filename subject {tcl_trace 0}} { set fd [open $filename r] sendmessage $toList $subject [read $fd] $trace return } }
Example Tcl Script for SNMP MIB Access
Using the Tcl shell, Tcl commands can perform actions on MIBs. The following example shows how to set up the community access strings to permit access to SNMP. Public access is read-only, but private access is read-write. The following example shows how to retrieve a large section of a table at once using the snmp_getbulk Tcl command extension.
Two arguments, non-repeatersand max-repetitions, must be set when an snmp_getbulk command is issued. The non-repeaters argument specifies that the first N objects are to be retrieved with a simple snmp_getnext operation. The max-repetitions argument specifies that up to M snmp_getnext operations are to be attempted to retrieve the remaining objects.
In this example, three bindings--sysUpTime (1.3.6.1.2.1.1.2.0), ifDescr (1.3.6.1.2.1.2.2.1.2), and ifType (1.3.6.1.2.1.2.2.1.3)--are used. The total number of variable bindings requested is given by the formula N + (M * R), where N is the number of non-repeaters (in this example 1), M is the max-repetitions (in this example 5), and R is the number of request objects (in this case 2, ifDescr and ifType). Using the formula, 1 + (5 * 2) equals 11; and this is the total number of variable bindings that can be retrieved by this snmp_getbulk request command.
Sample results for the individual variables include a retrieved value of sysUpTime.0 being 1336090, where the unit is in milliseconds. The retrieved value of ifDescr.1 (the first interface description) is FastEthernet0/0, and the retrieved value of ifType.1 (the first interface type) is 6, which corresponds to the ethernetCsmacd type.
snmp-server community public RO snmp-server community private RW tclsh snmp_getbulk public 1 5 1.3.6.1.2.1.1.2.0 1.3.6.1.2.1.2.2.1.2 1.3.6.1.2.1.2.2.1.3 {<obj oid='sysUpTime.0' val='1336090'/>} {<obj oid='ifDescr.1' val='FastEthernet0/0'/>} {<obj oid='ifType.1' val='6'/>} {<obj oid='ifDescr.2' val='FastEthernet1/0'/>} {<obj oid='ifType.2' val='6'/>} {<obj oid='ifDescr.3' val='Ethernet2/0'/>} {<obj oid='ifType.3' val='6'/>} {<obj oid='ifDescr.4' val='Ethernet2/1'/>} {<obj oid='ifType.4' val='6'/>} {<obj oid='ifDescr.5' val='Ethernet2/2'/>} {<obj oid='ifType.5' val='6'/>}
The following example shows how to retrieve the sysDescr.0, sysObjectID.0, sysUpTime.0, sysContact.0, sysName.0, and sysLocation.0 variables--in this example shown as system.1.0, system.2.0, system.3.0, system.4.0, system.5.0, and system.6.0--from the SNMP entity on the router using the snmp_getid Tcl command extension.
tclsh snmp_getid public {<obj oid='system.1.0' val='Cisco Internetwork Operating System Software Cisco IOS(tm) 7200 Software (C7200-IK9S-M), Experimental Version 12.3(20030507:225511) [geotpi2itd1 124] Copyright (c) 1986-2003 by Cisco Systems, Inc. Compiled Wed 21-May-03 16:16 by engineer'/>} {<obj oid='system.2.0' val='products.223'/>} {<obj oid='sysUpTime.0' val='6664317'/>} {<obj oid='system.4.0' val='1-800-553-2447 - phone the TAC'/>} {<obj oid='system.5.0' val='c7200.myCompany.com'/>} {<obj oid='system.6.0' val='Bldg 24, San Jose, CA'/>}
The following example shows how to retrieve a set of individual variables from the SNMP entity on the router using the snmp_getnext Tcl command extension:
snmp_getnext public 1.3.6.1.2.1.1.1.0 1.3.6.1.2.1.1.2.0 {<obj oid='system.2.0' val='products.223'/>} {<obj oid='sysUpTime.0' val='6683320'/>}
The following example shows how to retrieve a set of individual variables from the SNMP entity on the router using the snmp_getone Tcl command extension:
snmp_getone public 1.3.6.1.2.1.1.1.0 1.3.6.1.2.1.1.2.0 {<obj oid='system.1.0' val='Cisco Internetwork Operating System Software Cisco IOS(tm) 7200 Software (C7200-IK9S-M), Experimental Version 12.3(20030507:225511) [geotpi2itd1 124] Copyright (c) 1986-2003 by Cisco Systems, Inc. Compiled Wed 21-May-03 16:16 by engineer'/>} {<obj oid='system.2.0' val='products.223'/>}
The following example shows how to change something in the configuration of the router using the snmp_setany Tcl command extension. In this example, the hostname of the router is changed to TCLSNMP-HOST.
tclsh snmp_setany private 1.3.6.1.2.1.1.5.0 -d TCLSNMP-HOST {<obj oid='system.5.0' val='TCLSNMP-HOST'/>}
Additional References
The following sections provide references related to the Cisco IOS Scripting with Tcl feature.
Related Documents
Related Topic |
Document Title |
---|---|
Embedded Syslog Manager |
Embedded Syslog Manager module |
Network Management commands (including Tcl and logging commands): complete command syntax, defaults, command mode, command history, usage guidelines, and examples |
Cisco IOS Network Management Command Reference |
Standards
Standards |
Title |
---|---|
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
MIBs |
MIBs Link |
---|---|
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFCs |
Title |
---|---|
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
Feature Information for Cisco IOS Scripting with Tcl
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 4 | Feature Information for Cisco IOS Scripting with Tcl |
Feature Name |
Releases |
Feature Information |
---|---|---|
Cisco IOS Scripting with Tcl |
12.3(2)T 12.3(7)T 12.2(25)S 12.2(33)SXH 12.2(33)SRC 12.2(33)SB Cisco IOS XE 3.1.0SG |
The Cisco IOS Scripting with Tcl feature provides the ability to run Tcl version 8.3.4 commands from the Cisco IOS command-line interface. The following commands were introduced or modified: scripting tcl encdir, scripting tcl init, scripting tcl low-memory, tclquit, tclsh. |
Tcl SNMP MIB Access |
12.3(7)T 12.2(25)S 12.2(33)SXH 12.2(33)SRC 12.2(33)SB Cisco IOS XE 3.1.0SG |
The Tcl SNMP MIB Access feature introduces a set of UNIX-like SNMP commands to make access to Simple Network Management Protocol (SNMP) MIB objects easier. |
TCL UDP and VRF support |
15.1(1)T |
The Tcl UDP and VRF feature provides support for UDP sockets in IOS Tcl. The following commands were introduced or modified: fconfigure, socket, udp_open, udp_peek. |
Glossary
ESM --Embedded Syslog Manager.
IVR --Interactive Voice Response.
MIB --Management Information Base.
SNMP --Simple Network Management Protocol.
Tcl --Tool Command Language.
Note |
See Internetworking Terms and Acronyms for terms not included in this glossary. |
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.