Printing Out Subprocess When Regex Captures
I am running a bash command in python with: proc = subprocess.Popen(cmd) proc.wait() This cmd prints an output. However I dont want it to print unless it is captured by some regex
Solution 1:
You could do also pipe the output directly to grep etc..:
from subprocess import PIPE, Popen
p = Popen(["ps"], stdout=PIPE)
p2 = Popen(["grep", "chrome"],stdin=p.stdout, stdout=PIPE,universal_newlines=True)
p.stdout.close()
out,err = p2.communicate()
print(out)
421 ? 00:00:03 chrome
767 ? 00:00:02 chrome
843 ? 00:00:04 chrome
2788 ? 00:52:16 chrome
2819 ? 00:00:00 chrome-sandbox
2820 ? 00:00:00 chrome
2827 ? 00:00:00 chrome-sandbox
Solution 2:
You can do:
proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
To check any output/error you can apply your regex on (out,err)
, and print whatever you want.
hope this helps.
Solution 3:
In the simple case you should be able to use subprocess.check_output
to get the result of a call. In Python3 this returns a bytes
object. In Python2 it's a str
as usual.
# Python3
result_in_bytes = subprocess.check_output(cmd)
result = result_in_bytes.decode() # -> string
# Python2
result = subprocess.check_output(cmd)
Then you should be able to run your regex on that string.
Solution 4:
To emulate the shell pipeline:
#!/usr/bin/env python
from subprocess import Popen, PIPE
output = Popen("cmd | grep 'pattern'", shell=True,
stdout=PIPE).communicate()[0]
without the shell:
#!/usr/bin/env python
from subprocess import Popen, PIPE
grep = Popen(['grep', 'pattern'], stdin=PIPE, stdout=PIPE)
cmd_process = Popen(['cmd'], stdout=grep.stdin)
output = grep.communicate()[0]
cmd_process.wait()
Or you could filter cmd
's output in pure Python:
#!/usr/bin/env python
from subprocess import Popen, PIPE
matched_lines = []
cmd_process = Popen(['cmd'], stdout=PIPE)
with cmd_process.stdout:
for line in iter(cmd_process.stdout.readline, b''):
if b'pattern' in line: # or re.match(br'pattern', line)
matched_lines.append(line)
cmd_process.wait()
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