I need to store the result of a shell command that I executed in a variable, but I couldn't get it working. I tried like:
import os
call = os.system("cat syscall_list.txt | grep f89e7000 | awk '{print $2}'")
print call
But it prints the result in terminal and prints the value of call as zero, possibly indicating as success. How to get the result stored in a variable?
Use the subprocess module instead:
import subprocess
output = subprocess.check_output("cat syscall_list.txt | grep f89e7000 | awk '{print $2}'", shell=True)
Edit: this is new in Python 2.7. In earlier versions this should work (with the command rewritten as shown below):
import subprocess
output = subprocess.Popen(['awk', '/f89e7000/ {print $2}', 'syscall_list.txt'], stdout=subprocess.PIPE).communicate()[0]
As a side note, you can rewrite
cat syscall_list.txt | grep f89e7000
To
grep f89e7000 syscall_list.txt
And you can even replace the entire statement with a single awk script:
awk '/f89e7000/ {print $2}' syscall_list.txt
Leading to:
import subprocess
output = subprocess.check_output(['awk', '/f89e7000/ {print $2}', 'syscall_list.txt'])
AttributeError: 'module' object has no attribute 'check_output' 
['awk', '/f89e7000/ {print $2}', filename], and pass that to Popen().In python 3 you can use
import subprocess as sp
output = sp.getoutput('whoami --version')
print (output)
os.popen works for this. popen - opens a pipe to or from command. The return value is an open file object connected to the pipe, which can be read. split('\n') converts the output to list
import os
list_of_ls = os.popen("ls").read().split('\n')
print list_of_ls
import os
list_of_call = os.popen("cat syscall_list.txt | grep f89e7000 | awk '{print $2}'").read().split('\n')
print list_of_call
commands.getstatusoutput would work well for this situation. (Deprecated since Python 2.6)
import commands
print(commands.getstatusoutput("cat syscall_list.txt | grep f89e7000 | awk '{print $2}'"))
