Read/Write from/to a process
jas
codecraig at gmail.com
Mon Oct 24 13:38:43 EDT 2005
What about having a thread which reads from subprocess.Popen()'s
stdout...instead of read/write, read/write. just always read, and
write when needed?
any comments on that idea?
jas wrote:
> actually, i can't check for ">" only because if you a dir, a line can
> end with a > but is not the end of the output
>
> jas wrote:
> > Thanks, that is certainly a start. As you mentioned, the "cd" could is
> > an issue.
> >
> > Perhaps checking to see if the line ends with ">" is sufficient?
> >
> > Dennis Lee Bieber wrote:
> > > On 24 Oct 2005 07:20:42 -0700, "jas" <codecraig at gmail.com> declaimed the
> > > following in comp.lang.python:
> > >
> > > > Hi,
> > > > I would like to start a new process and be able to read/write from/to
> > > > it. I have tried things like...
> > > >
> > > > import subprocess as sp
> > > > p = sp.Popen("cmd.exe", stdout=sp.PIPE)
> > > > p.stdin.write("hostname\n")
> > > >
> > > > however, it doesn't seem to work. I think the cmd.exe is catching it.
> > >
> > > One: you didn't read any of the "returned" output...
> > >
> > > Two: the output only seems to be available upon EOF, which means the
> > > spawned command processor has to exit first... Though you CAN read one
> > > character at a time, and then have to build lines and expected prompt
> > > strings...
> > >
> > >
> > > This seems to work:
> > > -=-=-=-=-=-=-=-=-
> > > import subprocess
> > > import os
> > >
> > > PROMPT = os.getcwd() + ">"
> > >
> > > def getLine(proc):
> > > ld = []
> > > while True:
> > > c = proc.stdout.read(1)
> > > if c == "\r": continue #skip Windows <cr>
> > > if c != "\n": ld.append(c) #save all but <lf>
> > > if c is None or c == "\n" or c == ">": break
> > > ln = "".join(ld)
> > > return ln
> > >
> > > p = subprocess.Popen("cmd.exe", stdout=subprocess.PIPE, stdin =
> > > subprocess.PIPE)
> > >
> > > print "**** START of captured output"
> > > while True:
> > > ln = getLine(p)
> > > print ln
> > > if ln == PROMPT: break
> > > print "**** END of captured output"
> > >
> > > p.stdin.write("ipconfig\n")
> > > print "**** START of captured output"
> > > while True:
> > > ln = getLine(p)
> > > print ln
> > > if ln == PROMPT: break
> > > print "**** END of captured output"
> > >
> > > p.stdin.write("dir\n")
> > > print "**** START of captured output"
> > > while True:
> > > ln = getLine(p)
> > > print ln
> > > if ln == PROMPT: break
> > > print "**** END of captured output"
> > >
> > > p.stdin.write("exit\n")
> > > -=-=-=-=-=-=-=-=-=-
> > > E:\UserData\Dennis Lee Bieber\My Documents>python script1.py
> > > **** START of captured output
> > > Microsoft Windows XP [Version 5.1.2600]
> > > (C) Copyright 1985-2001 Microsoft Corp.
> > >
> > > E:\UserData\Dennis Lee Bieber\My Documents>
> > > **** END of captured output
> > > **** START of captured output
> > > ipconfig
> > >
> > > Windows IP Configuration
> > >
> > >
> > > Ethernet adapter Local Area Connection:
> > >
> > > Connection-specific DNS Suffix . :
> > > IP Address. . . . . . . . . . . . : 192.168.1.100
> > > Subnet Mask . . . . . . . . . . . : 255.255.255.0
> > > IP Address. . . . . . . . . . . . : fe80::211:11ff:fee1:f303%4
> > > Default Gateway . . . . . . . . . : 192.168.1.1
> > >
> > > Tunnel adapter Teredo Tunneling Pseudo-Interface:
> > >
> > > Connection-specific DNS Suffix . :
> > > IP Address. . . . . . . . . . . . :
> > > 3ffe:831f:4004:1956:0:fbde:bd0a:e50b
> > > IP Address. . . . . . . . . . . . : fe80::5445:5245:444f%5
> > > Default Gateway . . . . . . . . . : ::
> > >
> > > Tunnel adapter Automatic Tunneling Pseudo-Interface:
> > >
> > > Connection-specific DNS Suffix . :
> > > IP Address. . . . . . . . . . . . : fe80::5efe:192.168.1.100%2
> > > Default Gateway . . . . . . . . . :
> > >
> > > E:\UserData\Dennis Lee Bieber\My Documents>
> > > **** END of captured output
> > > **** START of captured output
> > > dir
> > > Volume in drive E is Data
> > > Volume Serial Number is 2626-D991
> > >
> > > Directory of E:\UserData\Dennis Lee Bieber\My Documents
> > >
> > > 10/24/2005 09:23 AM <DIR>
> > > .
> > > 10/24/2005 09:23 AM <DIR>
> > > ..
> > > 07/25/2005 10:39 PM <DIR>
> > > .metadata
> > > 10/06/2005 09:54 AM <DIR>
> > > Ada Progs
> > > 08/13/2005 02:01 PM <DIR>
> > > Agent Data
> > > 10/21/2005 09:29 AM 421,820 apress_offer.pdf
> > > 07/03/2005 11:36 AM 132 cp.py
> > > 07/17/2005 12:25 PM <DIR>
> > > Cyberlink
> > > 07/06/2005 09:32 AM 102,400 db1.mdb
> > > 07/26/2005 12:20 AM 26,614 eclipse_code.xml
> > > 10/24/2005 01:08 AM <DIR>
> > > Eudora
> > > 06/24/2005 08:50 PM 667 fake_oosums.ads
> > > 06/24/2005 08:50 PM 695 fake_oosums.ali
> > > 09/06/2005 09:01 PM <DIR>
> > > Genealogy
> > > 07/13/2005 10:56 PM <DIR>
> > > HomeSite
> > > 05/08/2005 01:05 PM <DIR>
> > > Investing
> > > 10/21/2005 10:04 PM <DIR>
> > > Java Progs
> > > 08/04/2005 10:13 PM 162 main.py
> > > 10/11/2005 10:43 PM <DIR>
> > > My Downloads
> > > 05/01/2005 10:31 AM <DIR>
> > > My eBooks
> > > 04/22/2005 12:09 AM <DIR>
> > > My Music
> > > 07/10/2005 11:43 AM <DIR>
> > > My Pictures
> > > 06/29/2005 11:55 PM <DIR>
> > > My PSP Files
> > > 05/23/2005 09:30 AM <DIR>
> > > My Videos
> > > 05/01/2005 12:49 PM <DIR>
> > > Office Documents
> > > 06/27/2005 03:19 PM 7,961,778
> > > org.eclipse.jdt.doc.user.I20050627-1435.pdf
> > > 06/27/2005 03:19 PM 6,791,109
> > > org.eclipse.platform.doc.user.I20050627-1435.pdf
> > > 10/11/2005 10:52 PM 56 oth_tsr_rm_750.ram
> > > 07/20/2005 09:32 AM 108,457 parkerred15yc.jpg
> > > 09/03/2005 10:36 PM <DIR>
> > > Python Progs
> > > 10/20/2005 10:38 PM <DIR>
> > > Quicken
> > > 07/10/2005 12:09 PM 3,356,248 results.xml
> > > 06/11/2005 12:03 PM 935 Scout_Ship Database.lnk
> > > 07/03/2005 12:38 PM <DIR>
> > > Scout_Ship My Documents
> > > 10/24/2005 09:23 AM 971 Script1.py
> > > 09/25/2005 12:40 PM 1,107 Script1_old.py
> > > 08/28/2005 11:47 AM <DIR>
> > > SimpleMu Logs
> > > 06/24/2005 08:56 PM 1,201 student_pack.ads
> > > 06/24/2005 08:49 PM 1,144 student_pack.ads.0
> > > 06/24/2005 08:56 PM 1,342 student_pack.ali
> > > 08/02/2005 11:39 PM 4,096 t.DOC
> > > 06/20/2005 10:11 AM 104 t.rx
> > > 08/05/2005 08:41 PM 66,452 Untitled-1.tif
> > > 08/05/2005 08:41 PM <DIR>
> > > VCheck
> > > 10/03/2005 02:58 AM <DIR>
> > > Visual Studio
> > > 10/03/2005 02:51 AM <DIR>
> > > Visual Studio 2005
> > > 21 File(s) 18,847,490 bytes
> > > 25 Dir(s) 267,162,845,184 bytes free
> > >
> > > E:\UserData\Dennis Lee Bieber\My Documents>
> > > **** END of captured output
> > >
> > > E:\UserData\Dennis Lee Bieber\My Documents>
> > >
> > > -=-=-=-=-=-=-=-=-
> > >
> > > Note that my "getLine()" has to return on either a real EOL, OR on
> > > the end of a command prompt ("stuff>"). I also had to initialize the
> > > prompt at the start. If someone issued a "cd" command to the subprocess,
> > > the prompt would be all out of sequence, and the code would hang.
> > >
> > > You'll also note that the prompt /ends/ a capture sequence, and the
> > > next command is the start of the /next/ capture sequence.
> > >
> > > --
> > > > ============================================================== <
> > > > wlfraed at ix.netcom.com | Wulfraed Dennis Lee Bieber KD6MOG <
> > > > wulfraed at dm.net | Bestiaria Support Staff <
> > > > ============================================================== <
> > > > Home Page: <http://www.dm.net/~wulfraed/> <
> > > > Overflow Page: <http://wlfraed.home.netcom.com/> <
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