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comgt - Option GlobeTrotter GPRS/EDGE/3G/HSDPA and Vodafone 3G/GPRS datacard

comgt(1) General Commands Manual comgt(1)


comgt - 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

turn on serial communications echo.

display summary help and exit.

don´t run the internal default script before an external script.

change to an alternate line terminator (default "0).

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

Print Version information.

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

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---

1@0000 set com 38400n81 let a=2 2@0025 print "9x",a,"=",9*a,"\n" 3@0051 sleep 5 4@0059 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" 9x2=18 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---

1@0000 inc n 2@0007 dec d3 3@0015 let a=58/3 4@0027 let $d="fod" 5@0041 let c=1/0 6@0052 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 : $cwd(). Example: cd "duh" if % != 0 print "Could not cd into duh.\n"
Command : close Description : closes file previously opened with open. Syntax : close file See Also : open.
Command : dec Description : Decrements the content of an integer variable by 1. Syntax : dec x Notes : x is from a to z or a0 to z9. Notes : Note that "let x=x-1" also works. See Also : let, inc.
Command : dump Description : Lists all non-zero integer variables and modified string Description : variables as log entries (standard error channel.) Syntax : dump See Also : abort, exit
Command : else Description : Alternatively execute commands if last "if" tested false. Syntax : else commands... See Also : if Example: if w<350 print "Wow! Imagine that.\n" else print "Rush Limbaugh is a big fat bastard.\n"
Command : eprint Description : print a comma-separated list of arguments on stderr. Syntax : eprint var,stringvar,"text",... Notes : Like print but on the standard error file descriptor. Notes : The error output can be re-directed with "2>file" on Notes : the command line. See Also : print.
Command : exec Description : Replaces current comgt process with another process. Syntax : exec "command -args..." See Also : system, fork. Example: #Finished script, call cu. exec "cu -l "+$dev()+" -s "+$baud()
Command : exit Description : terminates script execution with exit code. Syntax : exit exit_code See Also : abort, dump. Example: :error exit 1 :smeggit 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. Example: :disconnect 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(). Example: fork if % = -1 goto error if % = 0 goto child :parent ...
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. Example: 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. Example: gosub routine sleep 1 gosub routine goto end :routine print "Flim-flam!\n" return
Command : goto Description : Sends execution somewhere else in the script. Syntax : goto label See Also : :, gosub, return. Example: :win95 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(). Example: hset 0 :loop 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. Example: 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. Example: print "Enter your full name :" input $n4
Command : kill Description : Sends a signal to a process. Syntax : kill signal processID Notes : Both signal and processID are integer values. Same as Notes : standard unix kill except that signal aliases are not Notes : accepted and signal is not optional. Notes : 0 is returned in % if the signal could be sent, -1 Notes : otherwise. Notes : Signal 0 can be used to detect process existance. See Also : wait, pid(), ppid(). Example: fork let p=% if p = 0 goto child sleep 300 kill 15 p sleep 1 kill 0 p if % != 0 print "Child terminated\n" goto ok print "Could not terminate child!\n" kill 9 p sleep 1 kill 0 p if % = 0 print "Could not kill child!\n" goto error print "Child killed.\n" :ok ...
Command : let Description : Does a variable assignment. Syntax : let x=content Notes : x is [$]a0-z9. See Also : inc, dec. Example: 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. Example: 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. Example: 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(). Example: 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". Example: #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). Example: 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". Default=on. 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 |
Example: set echo off print "Password :" input $p print "\n" set echo on set comecho on set clocal on set senddelay 0.1 set ignorecase on set com 38400n81 set umask 022 # Must be octal (leading zero) ...
Note on clocal: If want your script to keep working after the carrier detect signal has dropped, set clocal on, otherwise, a CD drop causes the device line to close (hang up). This could happen if, let´s say, your script calls and connects, then disconnects or drops dtr (flash), then tries to re-connect again.
Command : sleep Description : Pauses execution. Syntax : sleep float_constant Notes : Float_constant is precise down to 1/100th sec, unless Notes : more than 100 seconds, in which case the precision Notes : falls down to 1 sec.
Example: sleep 0.06 sleep 3 sleep 86400 /* A whole day */
Command : system Description : Calls a system (unix) command Syntax : system "command" See Also : exec. Example: :dir print "listing of directory ",$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. Example: let n=1 :loop print n," sheep... ZZZzzz...\n" sleep n inc n testkey 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. Example: fork let p=% if p=0 goto child if p=-1 goto error print "Waiting for child to finish..." wait 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. Example: :dial 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. Example: :closecon 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 012345678901234567890123 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. -


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 <> wrote the original dcon utility.
Paul Hardwick <> updated it for the latest compilers, provided the built-in script functionality and tested it against GPRS and 3G datacards.
Martin Gregorie <> 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.
20 October, 2006 Debian Sid