comgt(1) Option GlobeTrotter GPRS/EDGE/3G/HSDPA and Vodafone 3G/GPRS datacard control tool


comgt -d device -ehstvVx script


-d device set the device to be used to communicate with the data-card. If not specified then comgt trys /dev/noz2, /dev/ttyUSB2 and then /dev/modem

-e turn on serial communications echo.

-h display summary help and exit.

-s don't run the internal default script before an external script.

-t change to an alternate line terminator (default ").

-v run in verbose mode. This traces scripts as they are executed. It is intended to help in debugging scripts.

-V Print Version information.

-x for internal and external scripts, any reference to 115200 baud is converted to 57600. This is useful for data cards that don't like 115200 baud such as the GlobeTrotter EDGE.


comgt is a scripting language interpreter useful for establishing communications on serial lines and through PCMCIA modems as well as GPRS and 3G datacards.

comgt has some features that are rarely found in other utilities of the same type.


- Pre-defined built-in scripts for 2G/3G datacard control
- Simple, BASIC-like script language.
- Command-line and file sourcing of script.
- Multi-response waitfor.
- waitquiet permits line stabilization.
- In-line text capture.
- Multi-process support: fork, wait, kill, exit.
- Debugging verbose and log output.
- logging to file.
- Flow control: goto, gosub, return, if, else.
- Low-impact on system resources.
- Time commands and functions.
- String manipulations.
- Environment manipulation: env(), putenv.
- External utilities system calls: system, exec.

Supported GPRS and 3G datacards

comgt has been tested against GlobeTrotter GPRS,EDGE, Combo EDGE, 3G, 3G EDGE, HSDPA and GlobeTrotter Fusion as well as Vodafone 3G. It can set the PIN and display information about datacards before a PPP connection is started. Additionally, because the GlobeTrotter and Vodafone 3G/GPRS datacard have a secondary serial interface, these datacards can be monitored while a PPP connection is in existence and transferring data.

comgt is primarily designed to work with the GlobeTrotter range of datacards but should be compatible with any other GPRS or 3G datacard provided its interface is implemented as one or more serial or USB serial devices and it is controlled and queried by an implementation of the Hayes command interface with the same AT command extensions used by the listed datacards.

Using comgt

comgt has only one function: to run a script. This may be one of a number of "standard" internal scripts or an external script. Both types of script are invoked in the same way. The "standard" scripts are built into comgt and will work for serially connected modems, built-in modems, PCMCIA modems as well as the GlobeTrotter GPRS and the Vodafone 3G/GPRS datacards. There is a search priority order for scripts - 1)internal, 2)working directory, 3)/etc/comgt

Built-in scripts

comgt This runs the default internal script. Running comgt without any script specified, e.g., comgt -d /dev/ttyS1 it will check for a PIN and prompt you if it is required. The next thing it does is wait for the device to register, it then reports the signal strength. If you don't specify a port with the -d option then /dev/modem is assumed. If the -s switch is not used then this default script is run before any external script.

comgt help Lists these and the other options available.

comgt info Lists the datacard configuration.

comgt sig Prints the signal strength.

comgt reg Prints the registration state.

comgt 3G Puts a GlobeTrotter 3G/Fusion and Vodafone 3G into 3G network only mode (UMTS/HSDPA).

comgt 2G Puts a GlobeTrotter 3G/Fusion and Vodafone 3G into 2G network only mode (GSM/GPRS/EDGE).

comgt 3G2G Puts a GlobeTrotter 3G/Fusion and Vodafone 3G into 3G preferred mode (UMTS/HSDPA and GSM/GPRS/EDGE).

comgt GTEDGE Use this command to initialise GlobeTrotter EDGE and GlobeTrotter Combo EDGE cards before doing anything else. (It switches on the radio).

comgt USA Switch to 900/1900 MHz band for USA operation. GlobeTrotter GPRS datacards only.

comgt EUROPE Switch to 900/1800 MHz band for European operation. GlobeTrotter GPRS datacards only.

comgt PIN Test the SIM PIN status and use the environment variable COMGTPIN as the value .

comgt APN Set the APN of the datacard to the value contained in the COMGTAPN environment variable.

Custom Scripts

As well as built in scripts you can make your own. The following script sets a Vodafone 3G datacard or Option Fusion card's UMTS mode to GPRS:

#Set GPRS only mode
set com 115200n81
set senddelay 0.05
waitquiet 1 0.2
send "AT_OPSYS=0^m"
print "Setting GPRS only mode"

If you saved the above script as GPRS you would call it like this:

comgt GPRS

If you needed to specify the port as well then do this:

comgt -d /dev/ttyS1 GPRS

You can also pass environment parameters to a comgt script via $env().

Replacing chat

chat is a utility that comes with the ppp package (for Linux, anyway) that, with a set of expect-send string couples, does enough to connect most people to ISPs and such. While chat's use is very simple, it isn't very flexible. That's where comgt takes over.

comgt can be used in place of chat using the same strategy. For example, a pppd line reading:

pppd connect \ 
     'chat -v "" ATDT5551212 CONNECT "" ogin: ppp \
     word: whitewater' \
     /dev/cua1 38400 debug crtscts modem defaultroute

Would, using comgt, read:

pppd connect 'comgt -s /root/scripts/isp.scr' /dev/cua1 38400 \
     debug crtscts modem defaultroute

And the isp.scr script would read:

     send "ATDT5551212^m"
     waitfor 60 "ogin:"
     send "ppp^m"
     waitfor 60 "word:"
     send "whitewater^m"

Of course it then becomes trivial to make this script a whole lot more functional by adding code for busy detect, re-dialing, etc...

Verbose output

When the verbose option is turned on, comgt reports everthing on the standard error channel. If turned on from the command line (-v), the output contains 4 sections.

- Command line argument actions These are actions taken because they were specified from the command line, such as opening a communication device (-d), etc... For these to be output, you must specify -v as the first argument.

- List of arguments The number and list of arguments passed. This is useful in case you have a bunch of environment variables or quotes, back-quotes, backslashes on the command line and you're not sure what the script really sees.

- Script list A list of the script to execute. This may be a concatenation of the default internal script, unless this is suppressed by the -s option, and a script file. Every line is listed with its line number and character position.

- Execution output List of commands as they are executed. The parser prints the line its currently on, starting from the exact point where its at to the end of the line. Multiple command groups on a single line produce multiple output lines. Verbose output may be mixed with script output (print, eprint or lprint.)

Here's an example:

$ comgt -v -d/dev/cua1 -s blah.scr
comgt 00:18:46 -> Verbose output enabled
comgt 00:18:46 -> Script file: blah.scr
comgt 00:18:46 -> argc:5
comgt 00:18:46 -> argv[0]=comgt
comgt 00:18:46 -> argv[1]=-v
comgt 00:18:46 -> argv[2]=-d/dev/cua1
comgt 00:18:46 -> argv[3]=-s
comgt 00:18:46 -> argv[4]=blah.scr
comgt 00:18:46 ->  ---Script---
[email protected] set com 38400n81 let a=2
[email protected] print "9x",a,"=",9*a,"\n"
[email protected] sleep 5
[email protected] exit 0
comgt 00:18:46 ->  ---End of script---
comgt 00:18:46 -> @0000 set com 38400n81 let a=2
comgt 00:18:46 -> @0017 let a=2
comgt 00:18:46 -> @0025 print "9x",a,"=",9*a,"\n"
comgt 00:18:46 -> @0051 sleep 5
comgt 00:18:51 -> @0059 exit 0

Programming manual


The syntax used for comgt scripts is rather simple, somewhat BASIC-like. A script is a non-tokenized, pure ASCII text file containing lines terminated by newline characters (Unix standard.) Scripts can be created and/or modified using any standard text editor (vi, vim, joe, pico, emacs, ed, microEmacs) Lines in a comgt script read like so:
 - Empty line
 - [indent]rem remark
 - [indent][[:|label] LABEL] [command [arguments]] rem remark
 - [indent][[:|label] LABEL] [command [arguments]] [command [arguments]]...
Characters used for indentation are the space and tabulation characters.
The rem command makes the script parser skip the rest of the line.
The rem command can also be written as "#" or "//".
Labels consist of lowercase and uppercase letters and digits.
Case is ignored in labels.
Commands and their arguments are separated by spaces and/or tabs.
Command groups are separated by spaces, tabs, or newlines.
Expressions must not contain spaces or tabs.
This is ok : let n=x+76
This is not: let n= x + 76
  Because this space ^ would terminate the let command group.

Error reporting

When comgt detects a script error, it immediately turns on verbose mode, generates a dump (see the dump command), reports the error in three lines and stops the execution. The first line reported is the command group being executed, the second one shows where the parser got and the third line reports the character position of the program counter, the error and the exit code.

Here's an example:

$ comgt -vs blar2.scr

Where the blar2.scr script is:

inc n 
dec d3 
let a=58/3 
let $d="fod" 
let c=1/0 
let $y4="sdfgsdfgsdfg"

The trace and error report looks like this:

comgt 11:20:15 -> Verbose output enabled
comgt 11:20:15 -> Script file: blar2.scr
comgt 11:20:15 -> argc:3
comgt 11:20:15 -> argv[0]=comgt
comgt 11:20:15 -> argv[1]=-vs
comgt 11:20:15 -> argv[2]=blar2.scr
comgt 11:20:15 ->  ---Script---
[email protected] inc n
[email protected] dec d3
[email protected] let a=58/3
[email protected] let $d="fod"
[email protected] let c=1/0
[email protected] let $y4="sdfgsdfgsdfg"
comgt 11:20:15 ->  ---End of script---
comgt 11:20:15 -> @0000 inc n
comgt 11:20:15 -> @0007 dec d3
comgt 11:20:15 -> @0015 let a=58/3
comgt 11:20:15 -> @0027 let $d="fod"
comgt 11:20:15 -> @0041 let c=1/0
comgt 11:20:15 -> -- Error Report --
comgt 11:20:15 -> ---->         ^
comgt 11:20:15 -> Error @49, line 5, Division by zero. (6)

Exit codes

When comgt terminates, it does so with an "exit code". That is a number passed back to the calling process to signify success or failures. In every-day Unix, 0 (zero) means success and everything else means whatever the author of the program wants it to mean. In a shell script, or directly on the command line, you may look at the content of $? after having called comgt to examine its exit code.


comgt /root/bin/call-isp
if [ $? != 0 ]; then
  echo "Oops! Something went wrong."

Internal comgt error codes are as follows:

0 : No problems whatsoever.  Apparently.
1 : Communication device problems.
2 : Console (tty) device problems.
3 : Memory problems.
4 : File or pipe problems.
5 : Syntax errors.
6 : Division by zero.
7 : Variable mis-management.
8 : System problems.  (Couldn't call /bin/sh or some such)


Command     : :   Alias: label
Description : Notes an anchor point for goto or gosub to branch to.
Syntax      : Keyword must not contain any special characters.
Note        : Must be first statement in a line.
See Also    : goto, gosub, return.
              gosub bravo
              print "The time is ",$time(),"\n"
              sleep 1
              goto loop
              label bravo
              print "Twonk!\n"
Command     : abort
Description : Causes comgt to call abort() and produce a core dump.
Syntax      : abort
See Also    : dump, exit.
Command     : cd
Description : Change directory.
Syntax      : cd directory
Notes       : -1 is returned in % if the change could not be made.
Notes       : directory is a string and thus could be a variable.
See Also    : $cwd().
              cd "duh"
              if % != 0 print "Could not cd into duh.\n"
Command     : close
Description : closes file previously opened with open.
Syntax      : close file
See Also    : open.
Command     : dec
Description : Decrements the content of an integer variable by 1.
Syntax      : dec x
Notes       : x is from a to z or a0 to z9.
Notes       : Note that "let x=x-1" also works.
See Also    : let, inc.
Command     : dump
Description : Lists all non-zero integer variables and modified string
Description : variables as log entries (standard error channel.)
Syntax      : dump
See Also    : abort, exit
Command     : else
Description : Alternatively execute commands if last "if" tested false.
Syntax      : else commands...
See Also    : if
              if w<350 print "Wow! Imagine that.\n"
              else print "Rush Limbaugh is a big fat bastard.\n"
Command     : eprint
Description : print a comma-separated list of arguments on stderr.
Syntax      : eprint var,stringvar,"text",...
Notes       : Like print but on the standard error file descriptor.  
Notes       : The error output can be re-directed with "2>file" on 
Notes       : the command line.
See Also    : print.
Command     : exec
Description : Replaces current comgt process with another process.
Syntax      : exec "command -args..."
See Also    : system, fork.
              #Finished script, call cu.
              exec "cu -l "+$dev()+" -s "+$baud()
Command     : exit
Description : terminates script execution with exit code.
Syntax      : exit exit_code
See Also    : abort, dump.
              exit 1
              exit 0
Command     : flash
Description : Toggles DTR on communication device for a specified time.
Syntax      : flash float_constant
Notes       : float_constant is precise down to 1/100th sec.
Notes       : Causes modem to drop carrier or go to command mode, 
Notes       : depending on modem settings.  Setting the baud rate to 0 
Notes       : for a time has the same effect.
See Also    : sleep, set com.
              flash 0.5
              exit 0
Command     : fprint
Description : print a comma-separated list of arguments in a file.
Syntax      : fprint var,stringvar,"text",...
Notes       : Like print but appended to a file previously opened 
Notes       : by open.
See Also    : print.
Command     : fork
Description : forks comgt process in two.  Both processes continue 
Description : executing the script.
Syntax      : fork
Notes       : % returns 0 for child process, new process ID for 
Notes       : parent or -1 for error.
See Also    : wait, kill, pid(), ppid().
              if % = -1 goto error
              if % = 0 goto child
Command     : get
Description : get string from communication device.
Syntax      : get timeout "terminators" $string
Notes       : timeout is a float constant, terminators is a 
Notes       : list of characters that, when received, terminate 
Notes       : get.  Terminators are ignored when received first.
See Also    : waitfor.
              waitfor 60 "connect"
              if % != 0 goto error
              get 2 " ^m" $s
              print "Connection parameters: ",$s,"\n"
Command     : gosub
Description : calls a subroutine.
Syntax      : gosub label
Notes       : Currently, comgt only supports 128 levels of gosub 
Notes       : calls (enough!)
See Also    : :, goto, return.
              gosub routine
              sleep 1
              gosub routine
              goto end
              print "Flim-flam!\n"
Command     : goto
Description : Sends execution somewhere else in the script.
Syntax      : goto label
See Also    : :, gosub, return.
              print "Today I want to go and use Linux, thank you.\n"
              goto win95
Command     : hset
Description : Set the hundreds timer.
Syntax      : hset value
Notes       : This command resets the hundreds of seconds timer to 
Notes       : a value for htime to start from.
See Also    : htime().
              hset 0
              print "Time in 1/100 of a sec.: ",htime(),"\n"
              sleep 0.01
              goto loop
Command     : if
Description : tests a condition
Syntax      : if test_condition commands...
Notes       : Conditionnaly executes commands if test condition is true.
Notes       : Test operators are = (equal), != (not equal), 
Notes       : <> (not equal to) < (less than), > (greater than), 
Notes       : <= (less or equal), >= (greater or equal).  
Notes       : All operators can be used with integers and strings.  
Notes       : If test_condition is false, if skips to
Notes       : the next line.
See Also    : else.
              if n>30 print "Oh-ho! too many sheep!\n" goto error
              if n=17 print "Hurray! we've enough sheep\n" goto party
              if n<17 print "Murray, get more sheep.\n" goto getmore
              if $z < "Marmaluke" goto ...
              if 3*a>5+b goto ...
Command     : inc
Description : increments the content of an integer variable by 1.
Syntax      : inc x
Notes       : x is a-z or a0-z9.
See Also    : dec, let.
Command     : input
Description : input string from keyboard into string variable.
Syntax      : input $x
Notes       : input terminates entry only with the ENTER key.  
Notes       : Spaces, tabs and other funny characters are all 
Notes       : stored in the variable.
See Also    : set echo.
              print "Enter your full name :"
              input $n4
Command     : kill
Description : Sends a signal to a process.
Syntax      : kill signal processID
Notes       : Both signal and processID are integer values.  Same as 
Notes       : standard unix kill except that signal aliases are not 
Notes       : accepted and signal is not optional.
Notes       : 0 is returned in % if the signal could be sent, -1 
Notes       : otherwise.
Notes       : Signal 0 can be used to detect process existance.
See Also    : wait, pid(), ppid().
              let p=%
              if p = 0 goto child
              sleep 300
              kill 15 p
              sleep 1
              kill 0 p
              if % != 0 print "Child terminated\n" goto ok
              print "Could not terminate child!\n"
              kill 9 p
              sleep 1
              kill 0 p
              if % = 0 print "Could not kill child!\n" goto error
              print "Child killed.\n"
Command     : let
Description : Does a variable assignment.
Syntax      : let x=content
Notes       : x is [$]a0-z9.
See Also    : inc, dec.
              let a=5
              let b=(time()-a)+5
              let y7=6809
              let z=0%11010111  #Binary
              let z=077324      #octal
              let z=0xf5b8      #hexadecimal
              let $c="Daniel "
              let $d=$c+" Chouinard"
              let $s5="Frimpin' Jeosaphat!"
Command     : lprint
Description : Print a comma-separated list of arguments to the log.
Syntax      : fprint var,stringvar,"text",...
Notes       : Like print but printed like a log entry if verbose is on.
Notes       : logging is sent to stderr.
See Also    : print, eprint, fprint.
Command     : open
Description : Opens a file or a communication device.
Syntax      : open com device, open com (stdin), open file FILE
See Also    : close.
              open com /dev/cua1
              set com 38400n81
              open file "/tmp/log"
              fprintf "This is a log\n"
              close file
Command     : print
Description : print a comma-separated list of arguments.
Syntax      : print var,stringvar,"text",...
Notes       : Spaces and newlines are not automatically added.
See Also    : eprint, fprint, lprint.
              let b=26
              let $c="text variables"
              print "Contstant text ",b," ",$c," time: ",$time(),"\n"
Command     : putenv
Description : Sets an environment variable.
Syntax      : putenv "var=content"
Notes       : Environment variables are automatically exported, 
Notes       : never returned. Children processes inherit the 
Notes       : environment.
See Also    : $env().
              putenv "SCRIPTDIR=/usr/lib/comgt/scripts"
              system "dothat"  # dothat reads env. var. SCRIPTDIR...
Command     : rem  Aliases: #, //
Description : Remark.  Rest of line is ignored.
Syntax      : Note that a space must follow "rem".
              #This is a remark
              // So is this
              rem This ain't no disco.
Command     : return
Description : Returns from subroutine.
Syntax      : return
See Also    : gosub.
Command     : send
Description : sends a string to the communication line (modem usually).
Syntax      : send string
Notes       : Carriage return (ENTER) is not sent automatically 
Notes       : (use ^m).
              send "atdt555-1212^m"
              send $g+"^m"
              send "The time is "+$time()+"^m^j"
Command     : set
Description : sets working parameters.
Syntax      : set parameter value
Notes       :
Command                       Description
----------------------------- -------------------------------------------------
set echo on|off               Keyboard echo on-screen.
set comecho on|off            Received characters echoed on-screen.
set senddelay time_constant   In-between character delay for "send"
set ignorecase on|off         Case sensitivity for "waitfor". 
set clocal on|off             clocal on = ignore modem signals
set umask mode                file mode creation defaults. 
                              See man umask.
set verbose on|off            verbose on = debug output enabled.
set com com_params            communication parameters. 
                                   ex.: 19200n81, 300e71
                                             baud |||
                                           Parity    |
                                        Data bits     |
                                        Stop bits      |
              set echo off
              print "Password :"
              input $p
              print "\n"
              set echo on
              set comecho on
              set clocal on
              set senddelay 0.1
              set ignorecase on
              set com 38400n81
              set umask 022 # Must be octal (leading zero)
Note on clocal:
  If want your script to keep working after the carrier detect 
  signal has dropped, set clocal on, otherwise, a CD drop causes 
  the device line to close (hang up).  This could happen if, 
  let's say, your script calls and connects, then disconnects or 
  drops dtr (flash), then tries to re-connect again.
Command     : sleep
Description : Pauses execution.
Syntax      : sleep float_constant
Notes       : Float_constant is precise down to 1/100th sec, unless
Notes       : more than 100 seconds, in which case the precision 
Notes       : falls down to 1 sec.
              sleep 0.06
              sleep 3
              sleep 86400 /* A whole day */
Command     : system
Description : Calls a system (unix) command
Syntax      : system "command"
See Also    : exec.
              print "listing of directory ",$cwd(),\n"
              system "ls -l |more"
Command     : testkey
Description : Tests keyboard for keystroke, returns 1 in % if present.
Syntax      : testkey
Notes       : Can only test for ENTER key.  Future versions of comgt 
Notes       : will test for more and return keycodes in %.
See Also    : input.
              let n=1
              print n," sheep... ZZZzzz...\n"
              sleep n
              inc n
              if % = 0 goto loop
Command     : wait
Description : Wait for a child process to terminate.
Syntax      : wait
Notes       : Process ID of terminated child is returned in %
See Also    : fork, kill.
              let p=%
              if p=0 goto child
              if p=-1 goto error
              print "Waiting for child to finish..."
              print "\n"
              if %!=p print "Wait got wrong PID!\n" goto error
              print "Child is done.\n"
Command     : waitfor
Description : Waits until one of a list of strings is received
Syntax      : waitfor timeout "string1","string2","string3"...
Notes       : Timeout is a floating time constant.  waitquiet returns
Notes       : 0 for the first string received, 1 for the second, etc...
Notes       : and -1 for a timeout.  Case is ignored by default unless
Notes       : ignorecase is set to off.
See Also    : get.
              send "atdt555-4411^m"
              waitfor 60 "no carrier","busy","no dial tone","connect"
              if % = -1 goto timedout
              if % = 0 goto nocd
              if % = 1 goto redial
              if % = 2 goto error
              if % = 3 goto connected
Command     : waitquiet
Description : Waits until communication line stops receiving for a time.
Syntax      : waitquiet timeout quiettime
Notes       : Both timeout and quiettime are floating time constants
Notes       : with 1/100th sec. accuracy.  Usefull for "swallowing" 
Notes       : incoming characters for a while or waiting for an 
Notes       : unknown prompt.
              send "logoff^m"
              waitquiet 10 0.5
              send "yes^m"

Integer functions

I-Function  : Access
Description : Verifies access rights to a file
Syntax      : let x=access("/tmp/file","frwx")
Notes       : The second string contains one or more of 
Notes       : 'f','r','w','x' to repectively check 
Notes       : existence, read, write and execute permissions.  
Notes       : Under root id, the only useful check is 'f', as
Notes       : all others will return true.
Return Value: 0 if the file exists, is readable, writable, 
Return Value: executable, or -1 if not.
See Also    : man access(2)
I-Function  : baud
Description : Returns current baudrate of communication line.
Syntax      : let x=baud()
Notes       : Does not necessarily match the modem connection speed.
See Also    : $baud().
I-Function  : len
Description : Returns the length of a string.
Syntax      : let x=len($s)
Notes       : "" is zero.  Strings currently have a maximum length of
Notes       : 1024 characters. comgt doesn't handle string overflow 
Notes       : at all.
I-Function  : htime
Description : Returns hundreds of seconds since start of script.
Syntax      : let x=htime()
Notes       : Set to a specific value with hset.
See Also    : hset.
I-Function  : pid
Description : Returns process ID number of current process (comgt)
Syntax      : let x=pid()
See Also    : ppid(), fork
I-Function  : ppid
Description : Returns process ID number of parent process.
Syntax      : let x=ppid()
Notes       : Can be used by forked child to detect parent 
Notes       : process.
I-Function  : time
Description : Returns time in seconds since Jan 1, 00:00:00 1970 GMT.
Syntax      : let x=time()
Notes       : Used to calculate time differences.
See Also    : $time()
I-Function  : val
Description : Returns value of string.
Syntax      : let x=val($x)
Notes       : String is not an expression; must only contain [0-9]
Notes       : characters. Future versions of comgt will be able to 
Notes       : evaluate expressions. (Maybe) (This was written 6 
Notes       : years ago.)
I-Function  : verbose
Description : Returns value of verbose setting.
Syntax      : let x=verbose()
Notes       : 0=off, 1=on.

String functions

S-Function  : basename
Description : Returns basename part of path.
Syntax      : let $x=$basename($p)
Notes       : $basename("/usr/bin/more")="more"
See Also    : $dirname().
S-Function  : baud
Description : Returns string representation of current baud rate.
Syntax      : let $x=$baud()
Notes       : Defined by "set com"
See Also    : baud(), set com.
S-Function  : cwd
Description : Returns current working directory pathname.
Syntax      : let $x=$cwd()
See Also    : cd.
S-Function  : dev
Description : Returns current communication device pathname.
Syntax      : let $x=$dev()
Notes       : defined by "-d" command line argument or "open com"
See Also    : open com.
S-Function  : dirname
Description : Returns directory name part of path.
Syntax      : let $x=$dirname($p)
Notes       : $dirname("/usr/bin/more")="/usr/bin"
See Also    : $basename().
S-Function  : env
Description : Returns content of an environment variable
Syntax      : let $x=$env("HOME")
Notes       : Non-existant variables return an empty string.
See Also    : putenv.
S-Function  : hex
Description : Converts value to hexadecimal representation
Syntax      : let $x=$hex(x)
Notes       : Letters a-f in lowercase, no preceding "0x"
See Also    : $hexu(), $oct().
S-Function  : hexu
Description : Converts value to hexadecimal representation
Syntax      : let $x=$hex(x)
Notes       : Letters A-F in uppercase, no preceding "0x"
See Also    : $hex(), $oct().
S-Function  : hms
Description : Converts number of seconds into time string
Syntax      : let $x=$hms(x)
Notes       : Format is "HH:MM:SS".  Useful for chronometer displays
Notes       : Use with "time()", do not try to increment a variable 
Notes       : every second using "sleep 1".  (See ISP script example)
Notes       : Format becomes "HHH:MM:SS" after 99 hours, 59 minutes, 
Notes       : 59s...
See Also    : time().
S-Function  : left
Description : Returns left portion of a string
Syntax      : let $x=$left($s,l)
Notes       : $s=Source string, l=length
Notes       : l must be less than the length of the string.
See Also    : $right(), $mid().
S-Function  : mid
Description : Returns midsection of a string.
Syntax      : let $x=$mid($s,s,l)
Notes       : $s=Source string, s=start, l=length
Notes       : s must be less than the length of the string, l can be
Notes       : some huge number (9999) to return the right side of a 
Notes       : string to the end.  the first character of a string is 
Notes       : position 0, not 1.
See Also    : $right(), $left().
S-Function  : oct
Description : Converts value to octal representation.
Syntax      : let $x=$oct(x)
See Also    : $hex(), $hexu().
S-Function  : right
Description : Returns right portion of a string.
Syntax      : let $x=$right($s,l)
Notes       : $s=Source string, l=length
Notes       : l must be less than the length of the string.
See Also    : $left(), $mid().
S-Function  : rpipe
Description : Returns the first line from a system piped command
Syntax      : let $x=$rpipe("/bin/ls |grep myfile")
Notes       : Not very useful unless used with head, tail, grep, 
Notes       : etc...
See Also    : system.
S-Function  : time
Description : Returns 24 character local time string
Syntax      : let $x=$time()
See Also    : time().
Notes       : Time is in this format: Mon Apr  8 14:21:22 1996
                                                1         2
S-Function  : tolower
Description : Returns lowercase'd string.
Syntax      : let $x=$tolower($y)
S-Function  : toupper
Description : Returns uppercase'd string.
Syntax      : let $x=$toupper($y)

Test operators

Operator Description       Example       Result
=        equal             if 1+2=3      yes
!=       not equal         if 1+2!=3     no
<>       not equal         if 1+2<>3     no
>        Greater than      if 1+3>3      yes
<        Less than         if 1+3<3      no
>=       Greater or equal  if 3>=3       yes
<=       Greater or equal  if 2<=3       yes
Strings can be compared using the same operators.
"aaa" < "aab",  "aaaa" > "aaa", "Test" != "test", "One" = "One", 
"A" > "a", "Fumble" <= "Fumigate", "Farsical" <> "Comedic"

Note that "set ignorecase on" does NOT apply to string comparisons.

Expression operators

Operator  Description      Example           Result
+         Addition         let a=2+2         4
+         Concatenation    let $b="aa"+"bb"  "aabb"
-         Substraction     let e=2-5         -3
*         Multiplication   let f=11*2        22
/         Division         let g=34/11       3
&         Bit-Wise AND     let h=42&7        2
|         Bit-Wise OR      let a=42|5        47
^         Bit-Wise XOR     let a=42^7        45

Mixed expression examples:

#Returns number of seconds since 00:00:00
let $t=$time() #Take a snapshot.
let a=(val(mid$($t,11,2))*3600)+(val(mid$($t,14,2))*60)+val(mid$($t,17,2))
#Notice the extra sets of parenthesis because comgt's expression 
#evaluator is brain-dead.
#For example, 5-2+1 should give you 4, right?  Well, according to 
#getvalue(), it actually gives 2, because it does it somewhat from 
#right to left.
#So to evaluate 5-2+1 correctly, use (5-2)+1.  If you're using 
#simple, two-element calculations, don't worry about it.  
#5-2 will give you 3.
#Concatenation  (Calls cu)
exec "cu -l "+$dev()+" -s "+$baud()"
#In a test condition
if a+c > strlen($c) goto toomuch
#String comparison
let $t=$mid($time(),11,8)
if $t > "19:59:59" print "Too late for that!\n" goto toolate
if $t < "08:00:00" print "Too early!\n" goto tooearly
if $t = "00:00:00" print "Oh god!  It's Twinkee time!\n"


The getvalue() parser. It makes me laugh so I think I'll leave it that way. - [email protected]


COMGTPIN - the 4 digit pin of the SIM for use by PIN script COMGTAPN - the APN to write to the data card, used by the APN script.


Daniel.Chouinard <[email protected]> wrote the original dcon utility.

Paul Hardwick <[email protected]> updated it for the latest compilers, provided the built-in script functionality and tested it against GPRS and 3G datacards.

Martin Gregorie <[email protected]> wrote the original manpage for comgt from the dcon documentation and packaged comgt for distribution.


Daniel Chouinard wrote most (90%) of dcon back in 1989 when he started doing Unix Apps tech support mostly by modem to customer systems. He was tired of typing all those passwords and funny call-charging codes everytime he used cu. Also, the company he worked for needed a system that would log call times and estimated costs. Thus dcon was born. Six or seven years later (1996) and he was using pppd to connect to his ISP site. He was more or less happy with chat but found it lacked flow control and multiple response checks from "atdt...". He wanted it to do different things for "no carrier", "no dial tone", and "busy". Although he thought that chat would probably be enhanced someday, when he found dcon.c on one of his old 45M tapes he tried compiling it on his Linux box and, lo and behold, it did. In the end, he added a few things to it (kill, fork, wait, 1/100 sec. times) and left it at that.

A couple of years ago Paul Hardwick found the program, dcon 0.97, last modified in 1996. The purpose of this program was to run scripts that would control Linux serial ports. The implementation was very similar to something he had written for Windows. Anyway, rather than reinvent he contacted the author, Daniel Chouinard, and asked his permission to reuse the code. Happily he gave permission and a basic but useful utility called comgt was created. Paul takes no credit for the engine, apart from making it compatible with todays compilers. It is basically dcon repackaged.