Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!dali.cs.montana.edu!caen!sol.ctr.columbia.edu!ira.uka.de!fauern!math.fu-berlin.de!uniol!Norbert.Zacharias From: Norbert.Zacharias@arbi.informatik.uni-oldenburg.de (Norbert Zacharias) Newsgroups: comp.os.msdos.programmer Subject: Re: DOS Environment Variables Message-ID: Date: 10 May 91 08:44:16 GMT References: <91125.051531AURPS@ASUACAD.BITNET> <2280@gold.gvg.tek.com> Organization: University of Oldenburg, Germany Lines: 212 shaunc@gold.gvg.tek.com (Shaun Case) writes: >In article <91125.051531AURPS@ASUACAD.BITNET> AURPS@ASUACAD.BITNET writes: >>Does anyone know how to permanently change a DOS environment variable from >>within an executing program? PUTENV() changes/creates a variable but it >>is only in effect while the program is running. As soon as I go back to >>DOS, the environment is restored to its original variables. I'm using >>Turbo C. The problem is to find the environmentspace of command.com because of the PUTENV() works on the environment of the current program. Sometimes ago i read an program in the Ct (a german computer magazin) witch deals with this task. I think it was in 1988 or 87. If i able to find this article i'll post it Norbert >I've tried a few things, and the following is what has worked for me. It >also happens to be portable betweem different MSDOS C compilers and versions >of MSDOS. >Additionally, this is really an MSDOS-specific question, so I have directed >followups to comp.os.msdos.programmer. >To set a master environment variable, try using the following batchfile >with your program: >File GO.BAT: >------------- cut here -------------- >echo off >REM use '@echo off' if you have dos 3.3 or higher >set >REM your program name here: >test >command /c setvar >REM use 'call setvar' if you have dos 3.3 or higher >set >------------- cut here -------------- >here is test.c: >------------- cut here -------------- >/********************* > set_env_var.c > Shaun Case, 1991 > Public Domain > *********************/ >#include >int main() >{ > FILE *batfile; > char varname[134]; > char value[134]; > printf("\nEnter variable name: "); > gets(varname); > printf("Enter value: "); > gets(value); > puts(""); > if ((batfile = fopen("SETVAR.BAT", "w")) == NULL) > { > puts("Unable to open SETVAR.BAT, Omot. Bailing.\n\n"); > return 1; > } > fprintf(batfile, "SET %s=%s\n", varname, value); > fclose(batfile); > return 0; >} >------------- cut here -------------- >I got the following output: >COMSPEC=C:\4DOS.COM >CMDLINE=go >PATH=f:\tmp;c:\sys\util;c:\sys\bat;d:\borlandc\bin;d:\tc;C:\DOS;C:\WIN386;C:\;C:\TCP;c:\vga;c:\f-prot >TEMP=f:\tmp >TMP=f:\tmp >FTPINIT=c:\tcp\init.tbl >FTP_ATTR=0x71,0x74,0x21 >FTP_CONFIG=c:\tcp\ftp.cfg >USER=@Man >PROMPT=$p$g >Enter variable name: hodag >Enter value: badger_nemesis >COMSPEC=C:\4DOS.COM >CMDLINE=setvar >PATH=f:\tmp;c:\sys\util;c:\sys\bat;d:\borlandc\bin;d:\tc;C:\DOS;C:\WIN386;C:\;C:\TCP;c:\vga;c:\f-prot >TEMP=f:\tmp >TMP=f:\tmp >FTPINIT=c:\tcp\init.tbl >FTP_ATTR=0x71,0x74,0x21 >FTP_CONFIG=c:\tcp\ftp.cfg >USER=@Man >PROMPT=$p$g >HODAG=badger_nemesis >-- >shaunc@gold.gvg.tek.com atman%ecst.csuchico.edu@RELAY.CS.NET >Postmaster of 1:119/666 1@9651 (WWIVnet) >It's enough to destroy a young moose's faith! -- Bullwinkle -- ============================================================================= Norbert Zacharias Norbert.Zacharias@arbi.informatik.uni-oldenburg.de FB Physik 148964@DOLUNI1.bitnet Carl-von-Ossietzky-Universitaet Tel. 0049-441-7983527 Was Du nicht willst das man Dir tu, das will auch nicht was willst denn Du? Heinz Erhard =============================================================================