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I'm getting errors when reading from/writing to pipes that are fairly
large in size. To bypass this, I wanted to redirect output to a file
in the subprocess.Popen function, but couldn't get it to work (even
after setting Shell=True). I tried adding ">","temp.sql" after the
password field but mysqldump gave me an error.

the code:
p1 = subprocess.Popen(["mysqldump","--all-databases","--user=user","--
password=password"], shell=True)
p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout)
output = p2.communicate()[0]
file=open('test.sql.gz','w')
file.write(str(output))
file.close()

the output:
gzip: compressed data not written to a terminal. Use -f to force
compression.
For help, type: gzip -h
mysqldump: Got errno 32 on write

I'm using python rather than a shell script for this because I need to
upload the resulting file to a server as soon as it's done.

thanks

En Mon, 07 Apr 2008 20:52:54 -0300, skunkwerk <>
escribió:

> I'm getting errors when reading from/writing to pipes that are fairly
> large in size. To bypass this, I wanted to redirect output to a file
> in the subprocess.Popen function, but couldn't get it to work (even
> after setting Shell=True). I tried adding ">","temp.sql" after the
> password field but mysqldump gave me an error.
>
> the code:
> p1 = subprocess.Popen(["mysqldump","--all-databases","--user=user","--
> password=password"], shell=True)
> p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout)
> output = p2.communicate()[0]
> file=open('test.sql.gz','w')
> file.write(str(output))
> file.close()

You need a pipe to chain subprocesses:

import subprocess
p1 =
subprocess.Popen(["mysqldump","--all-databases","--user=user","--password=password"],
stdout=subprocess.PIPE)
ofile = open("test.sql.gz", "wb")
p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout, stdout=ofile)
p1.wait()
p2.wait()
ofile.close()

If you don't want the final file on disk:

p1 =
subprocess.Popen(["mysqldump","--all-databases","--user=user","--password=password"],
stdout=subprocess.PIPE)
p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout,
stdout=subprocess.PIPE)
while True:
chunk = p2.stdout.read(4192)
if not chunk: break
# do something with read chunk

p1.wait()
p2.wait()

--
Gabriel Genellina

On Apr 7, 6:17*pm, "Gabriel Genellina" <gagsl-...@yahoo.com.ar> wrote:
> En Mon, 07 Apr 2008 20:52:54 -0300,skunkwerk<skunkw...@gmail.com> *
> escribió:
>
> > I'm getting errors when reading from/writing to pipes that are fairly
> > large in size. *To bypass this, I wanted to redirect output to a file
> > in the subprocess.Popen function, but couldn't get it to work (even
> > after setting Shell=True). *I tried adding ">","temp.sql" after the
> > password field but mysqldump gave me an error.
>
> > the code:
> > p1 = subprocess.Popen(["mysqldump","--all-databases","--user=user","--
> > password=password"], shell=True)
> > p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout)
> > output = p2.communicate()[0]
> > file=open('test.sql.gz','w')
> > file.write(str(output))
> > file.close()
>
> You need a pipe to chain subprocesses:
>
> import subprocess
> p1 = *
> subprocess.Popen(["mysqldump","--all-databases","--user=user","--password=password"], *
> stdout=subprocess.PIPE)
> ofile = open("test.sql.gz", "wb")
> p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout, stdout=ofile)
> p1.wait()
> p2.wait()
> ofile.close()
>
> If you don't want the final file on disk:
>
> p1 = *
> subprocess.Popen(["mysqldump","--all-databases","--user=user","--password=password"], *
> stdout=subprocess.PIPE)
> p2 = subprocess.Popen(["gzip","-9"], stdin=p1.stdout, *
> stdout=subprocess.PIPE)
> while True:
> * *chunk = p2.stdout.read(4192)
> * *if not chunk: break
> * *# do something with read chunk
>
> p1.wait()
> p2.wait()
>
> --
> Gabriel Genellina

thanks Gabriel - tried the first one and it worked great!