Last week (well it was last week when I started writing this) we had an issue come into the CAC where someone wanted to write a command macro that ran telnet to log into a system and execute some commands, for example the command macro test.cm logins into a remote host and executes the foo.cm command macro.
&attach_input
telnet 192.168.77.128
password
foo.cm
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Figure 1 – telnet command macro test.cm |
display_line display_system_usage
display_system_usage
display_line netstat -statistics -protocol tcp
netstat -statistics
display_line analyze_system -request_line 'stcp_meters -all -long' -quit
analyze_system -request_line 'stcp_meters' -quit
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Figure 2 – foo.cm |
Unfortunately telnet is not designed to execute in a command macro and it fails.
test
telnet: fatal error - tcgetattr failed
Error on line 3 of test.
command_processor: Object not found. password. In command macro
%azvos#m17_mas>SysAdmin>Noah_Davids>test.cm
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Figure 3 – execution of test.cm fails |
There are however several ways that automagic login into a remote host followed by command execution can be done.
send_cmds.c:
I wrote a program a while back that makes a connection to a telnet server, sends strings, and parses the output. The scripting language is simple but for simple things it works fine. The source code with more extensive examples can be found here
The script is basically a send string followed by a wait string. The script advances to the next line when the wait string is seen, as I said very simple. The script does have arguments, in figure 4 I use arg0 for the password so my password is not stored in the script. Execution of the script follows in figure 5. I truncated the output of each command in the interest of saving space. You will notice that the non-control characters from the character positioning strings are displayed until I set the terminal type to ascii.
//login
/login nd/Password?
/arg0/ready
/set_terminal_parameters -terminal_type ascii -pause_lines 0/ready
/foo.cm/ready
/quit/quit
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Figure 4 – send_cmds script to login and execute the foo command macro |
send_cmds -IPAddress 192.168.77.128 -InputFilePath test.send_cmds -no_Verbose -a
+rg0 password
PHOENIX CAC VOS TEST SYSTEM (%phx_vos#m16)
*** To boot on a different VOS Release see ***
*** >Overseer>COMMON>cfg>reconfig_instructions ***
OpenVOS Release 17.1.0ax, Module %phx_vos#m16
Please login 08:15:01
login nd
Password?
Noah_Davids.CAC logged in on %phx_vos#m16 at 13-04-21 08:15:01 mst.
[f[J[?7l[20l=[1m[1;24r[f[J[J[24;80f
[0;1mready 08:15:01
[0mset_terminal_parameters -terminal_type ascii -pause_lines 0
[1mset_terminal_parameters -terminal_type ascii -pause_lines 0
ready 08:15:01
foo.cm
display_system_usage
Usage statistics for module %phx_vos#m16, G94330, OpenVOS Release 17.1.0ax
All 762.6 hours (31.7 days) up.
----CPU----- Last Min Last 5 Min Last Hour All Up Time
. . . . .
Int. Time 0.00 0.1% 0.02 0.1% 0.23 0.1% 191.65 0.1%
netstat -statistics
tcp:
. . . .
201766 tcpOutRsts
analyze_system -request_line stcp_meters -all -long -quit
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 884, ptep 8D3E6000, Noah_Davids.CAC
stcp_meters %phx_vos#m16 762:36:19 13-04-21 08:15:02
. . . .
bufdat executed 678 (avg 0.0002/sec)
ready 08:15:02
ready 08:15:03
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Figure 5 – send_cmds execution |
expect:
There is a program called expect in the gnu_library. The syntax for an expect script can be very complex, it allows for branching based on different return strings so you can intelligently handle errors instead of just timing out. You can check out the web for examples, just search for “expect script examples”. I will present a simple script that just logs in and executes the foo.cm macro. Note that there were some bugs in early versions of gnu_tools (which is why I wrote send_cmds) but as of release 3.4.0a you should be OK. While I do not show it, expect can also use arguments so the password does not have to be part of the script or the script can prompt you for a password. Again I truncated the command output from the script and you can see that the non-control characters from the character positioning strings are displayed until I set the terminal type to ascii. Expect however filters the string differently so not all the characters are shown.
spawn "telnet"
expect "telnet>"
send "open 192.168.77.128r"
expect "login"
send "login ndr"
expect "Password"
send "passwordr"
expect "ready"
send "set_terminal_parameters -terminal_type ascii -pause_lines 0r"
expect "ready"
send "foo.cmr"
expect "ready"
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Figure 6 – expect script to login and execute the foo command macro |
>bin>expect test.expect
spawn telnet
telnet> open 192.168.77.128
Trying...
Connected to 192.168.77.128.
Escape character is '^]'.
PHOENIX CAC VOS TEST SYSTEM (%phx_vos#m16)
*** To boot on a different VOS Release see ***
*** >Overseer>COMMON>cfg>reconfig_instructions ***
OpenVOS Release 17.1.0ax, Module %phx_vos#m16
Please login 08:51:28
login nd
Password?
Noah_Davids.CAC logged in on %phx_vos#m16 at 13-04-21 08:51:28 mst.
fJ?7l20l
0;1mready 08:51:28
1mset_terminal_parameters -terminal_type ascii -pause_lines 0
ready 08:51:28
foo.cm
display_system_usage
Usage statistics for module %phx_vos#m16, G94330, OpenVOS Release 17.1.0ax
All 763.2 hours (31.8 days) up.
----CPU----- Last Min Last 5 Min Last Hour All Up Time
. . . .
Int. Time 0.00 0.1% 0.02 0.1% 0.24 0.1% 191.80 0.1%
netstat -statistics
tcp:
. . . .
201926 tcpOutRsts
analyze_system -request_line stcp_meters -all -long -quit
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 895, ptep 8D2E1200, Noah_Davids.CAC
stcp_meters %phx_vos#m16 763:12:46 13-04-21 08:51:29
. . . .
bufdat executed 678 (avg 0.0002/sec)
ready 08:51:29
ready 08:51:29
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Figure 7 – expect script execution |
SSH:
Finally you can use SSH to execute a command on a remote system. If you have also set up public key authentication you are not prompted for a password at the time of execution.
There are a number of interesting wrinkles when using SSH. First abbreviations do not work, don’t try to execute dps, use display_print_status.
ssh [email protected] dbs
sh: dbs: command not found
ready 12:26:25
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Figure 8 – Using SSH to remotely execute a command abbreviation doesn’t work |
ssh [email protected] display_batch_status
Batch queues for %phx_vos#m16
QUEUE STATE MAX RUNNING JOBS
normal run 5
ready 12:26:43
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Figure 9 – Using SSH to remotely execute a command does work |
Second, executing a command macro directly doesn’t work; note there is no output and it appears that only the first command in the macro was even processed.
ssh [email protected] 'foo.cm'
display_system_usage
ready 12:08:40
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Figure 10 – Using SSH to remotely execute a command macro doesn’t always work |
Instead you have to execute the shell command and provide the command macro as its argument.
ssh [email protected] '/bin/sh foo.cm'
display_system_usage
Usage statistics for module %phx_vos#m16, G94330, OpenVOS Release 17.1.0ax
All 766.5 hours (31.9 days) up.
----CPU----- Last Min Last 5 Min Last Hour All Up Time
CPU minutes 0.02 0.5% 0.09 0.4% 0.91 0.4% 724.76 0.4%
. . . .
Int. Time 0.00 0.1% 0.02 0.1% 0.23 0.1% 192.57 0.1%
netstat -statistics
tcp:
. . . .
202796 tcpOutRsts
analyze_system -request_line stcp_meters -all -long -quit
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 922, ptep 8D3C2780, Noah_Davids.CAC
stcp_meters %phx_vos#m16 766:30:14 13-04-21 12:08:57
. . . .
bufdat executed 678 (avg 0.0002/sec)
ready 12:08:59
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Figure 11 – Using SSH to remotely execute a command macro by executing it as a shell script |
Complex macros will not work. For example each line of the command macro is forked as a separate process so macros that use the process_dir to hold intermediate results will not work. Note that each invocation of analyze_system is reporting a different process number.
ssh [email protected] '/bin/sh foo3.cm'
%phx_vos#m16_mas>SysAdmin>Noah_Davids>foo3.cm 13-04-21 12:52:20 mst
display foo3.cm
display_line
analyze_system -request_line '' -quit
analyze_system -request_line '' -quit
analyze_system -request_line '' -quit
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 1028, ptep 8D3C3000, Noah_Davids.CAC
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 1029, ptep 8D3C3000, Noah_Davids.CAC
OpenVOS Release 17.1.0ax, analyze_system Release 17.1.0ax
Current process is 1030, ptep 8D3C3000, Noah_Davids.CAC
ready 12:52:21
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Figure 12 – Each command in the macro is forked as a separate process |
Using command macros with VOS style variables will generate syntax errors since the shell doesn’t know what they are. The foo3.cm command macro displays itself and then counts to 9. The display command is executed and the “&set” generates a syntax error.
ssh [email protected] '/bin/sh foo3.cm'
%phx_vos#m16_mas>SysAdmin>Noah_Davids>foo3.cm 13-04-22 07:33:18 mst
display foo3.cm
&set COUNT 1
&label again
display_line &COUNT&
&set COUNT (calc &COUNT& + 1)
&if &COUNT& < 10 &then &goto again
foo3.cm: line 2: syntax error near unexpected token `&s'
foo3.cm: line 2: `&set COUNT 1'
ready 07:33:18
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Figure 13 – Command macros with VOS style variables will not work |
But using shell variables will work. That of course may require extensive rewrites of existing macros. Here is an example of the same macro as a shell script.
ssh [email protected] '/bin/sh foo3u'
cat foo3u
count=1
while [[ $count -le 9 ]]
do
echo "$count"
(( count++ ))
done
1
2
3
4
5
6
7
8
9
ready 07:44:41
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Figure 14 – Shell script with shell stype variables does work |
However, you can run your VOS style command macro as a started process and then display the outfile that is produced. The macro start_foo3.cm runs start_process, waits for the process to terminate and then displays the output file without a header. I have modified the foo3.cm to turn off the command and macro lines and also the ready prompt to more fully mimic the output from a command macro run interactively.
start_process foo3.cm -wait
display foo3.out -no_header
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Figure 15 – Command macro to run foo3.cm as a started process |
With the exception of the login header and the command macro name on the first 2 lines and the “Process finished” line at the end the results are the same as if you ran the macro from the VOS command line.
ssh [email protected] '/bin/sh start_foo3.cm'
Noah_Davids.CAC logged in on %phx_vos#m16 at 13-04-22 10:45:23 mst.
foo3.cm
%phx_vos#m16_mas>SysAdmin>Noah_Davids>foo3.cm 13-04-22 10:45:23 mst
&echo no_input_lines no_command_lines no_macro_lines
set_ready -format off
display foo3.cm
&set COUNT 1
&label again
display_line &COUNT&
&set COUNT (calc &COUNT& + 1)
&if &COUNT& < 10 &then &goto again
1
2
3
4
5
6
7
8
9
Process finished.
ready 10:45:25
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Figure 16 – Results of running foo.cm in a started process |
So, as you can see while you cannot use telnet that are other ways to automagically login and execute commands.