gcom

Langue: en

Version: 04 January, 2006 (debian - 07/07/09)

Section: 1 (Commandes utilisateur)

Sommaire

• NAME
• SYNOPSIS
• OPTIONS
• DESCRIPTION
• • Features
  • Supported GPRS and 3G datacards
  • Using gcom
  • Built-in scripts
  • Custom Scripts
  • Replacing chat
  • Verbose output
• Programming manual
• • Syntax
  • Error reporting
  • Exit codes
  • Commands
  • Integer functions
  • String functions
  • Test operators
  • Expression operators
• KNOWN FEATURES
• AUTHORS
• • History

NAME

gcom - Option GlobeTrotter GPRS/EDGE/3G/HSDPA and Vodafone 3G/GPRS datacard control tool

SYNOPSIS

gcom -d device -ehstvx script

OPTIONS

-d device set the device to be used to communicate with the data-card. Defaults to /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.

-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.

DESCRIPTION

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

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

Features

 - 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

gcom 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.

gcom 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 gcom

gcom 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 gcom and will work for serially connected modems, built-in modems, PCMCIA modems as well as the GlobeTrotter GPRS and the Vodafone 3G/GPRS datacards.

Built-in scripts

gcom This runs the default internal script. Running gcom without any script specified, e.g.,gcom -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.

gcom help Lists these and the other options available.

gcom info Lists the datacard configuration.

gcom sig Prints the signal strength.

gcom reg Prints the registration state.

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

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

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

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

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

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

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:

gcom GPRS

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

gcom -d /dev/ttyS1 GPRS

You can also pass environment parameters to a gcom 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 gcom takes over.

gcom 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 gcom, read:

 pppd connect 'gcom /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, gcom 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:

 $ gcom -v -d/dev/cua1 -s blah.scr gcom 00:18:46 -> Verbose output enabled gcom 00:18:46 -> Script file: blah.scr gcom 00:18:46 -> argc:5 gcom 00:18:46 -> argv[0]=gcom gcom 00:18:46 -> argv[1]=-v gcom 00:18:46 -> argv[2]=-d/dev/cua1 gcom 00:18:46 -> argv[3]=-s gcom 00:18:46 -> argv[4]=blah.scr gcom 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 gcom 00:18:46 ->  ---End of script--- gcom 00:18:46 -> @0000 set com 38400n81 let a=2 gcom 00:18:46 -> @0017 let a=2 gcom 00:18:46 -> @0025 print "9x",a,"=",9*a,"\n" 9x2=18 gcom 00:18:46 -> @0051 sleep 5 gcom 00:18:51 -> @0059 exit 0 

Programming manual

Syntax

The syntax used for gcom scripts is rather simple, somewhat BASIC-like. A script is a non-tokenized, pure ASCII text file containing lines terminated by newline characters (Unixstandard.) Scripts can be created and/or modified using any standard text editor (vi, vim, joe, pico, emacs, ed, microEmacs) Lines in a gcom 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 gcom 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:

 $ gcom -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:

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

Exit codes

When gcom 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 gcom to examine its exit code.

Example:

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

Internal gcom 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) 

Commands

 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. Example:               :loop               gosub bravo               print "The time is ",$time(),"\n"               sleep 1               goto loop               label bravo               print "Twonk!\n"               return  Command     : abort Description : Causes gcom 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    : $cwd(). Example:               cd "duh"               if % != 0 print "Could not cd into duh.\n"   Command     : close Description : closes file previously opened with open. Syntax      : close file See Also    : open.   Command     : dec Description : Decrements the content of an integer variable by 1. Syntax      : dec x Notes       : x is from a to z or a0 to z9. Notes       : Note that "let x=x-1" also works. See Also    : let, inc.   Command     : dump Description : Lists all non-zero integer variables and modified string Description : variables as log entries (standard error channel.) Syntax      : dump See Also    : abort, exit   Command     : else Description : Alternatively execute commands if last "if" tested false. Syntax      : else commands... See Also    : if Example:               if w<350 print "Wow! Imagine that.\n"               else print "Rush Limbaugh is a big fat bastard.\n"   Command     : eprint Description : print a comma-separated list of arguments on stderr. Syntax      : eprint var,stringvar,"text",... Notes       : Like print but on the standard error file descriptor.   Notes       : The error output can be re-directed with "2>file" on  Notes       : the command line. See Also    : print.   Command     : exec Description : Replaces current gcom process with another process. Syntax      : exec "command -args..." See Also    : system, fork. Example:               #Finished script, call cu.               exec "cu -l "+$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 gcom 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, gcom 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/gcom/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 gcom  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. gcom 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 (gcom) 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 gcom 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 gcom'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" 

KNOWN FEATURES

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

AUTHORS

Daniel.Chouinard <[e-mail]> wrote the original dcon utility.

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

Martin Gregorie <[e-mail]> wrote the original manpage for gcom from the dcondocumentation and packaged gcom for distribution.

History

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 chatwould 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 gcom was created. Paul takes no credit for the engine, apart from making it compatible with todays compilers. It is basicallydcon repackaged.