Python Forum

Hi all,

I want to pass a variable to this command :

VARIABLE=12
v_num_final_distinct_grid_disks_per_cell_and_dg = subprocess.check_output("cat /tmp/logall | sort -u | grep -v VARIABLE", shell=True);

How can I do that?
I tried:

VARIABLE=12
v_num_final_distinct_grid_disks_per_cell_and_dg = subprocess.check_output("cat /tmp/logall | sort -u | grep -v %s",VARIABLE, shell=True);

But didnt work.

String formatting and now use f-string new in Python 3.6 ➡

>>> VARIABLE = 12
>>> s = f"cat /tmp/logall | sort -u | grep -v {VARIABLE}"
>>> s
'cat /tmp/logall | sort -u | grep -v 12'

(Apr-11-2022, 11:53 PM)snippsat Wrote: [ -> ]String formatting and now use f-string new in Python 3.6 ➡

>>> VARIABLE = 12
>>> s = f"cat /tmp/logall | sort -u | grep -v {VARIABLE}"
>>> s
'cat /tmp/logall | sort -u | grep -v 12'

Is there a way to in python 2.7? I cannot use 3 yet.

(Apr-12-2022, 11:32 AM)paulo79 Wrote: [ -> ]

(Apr-11-2022, 11:53 PM)snippsat Wrote: [ -> ]String formatting and now use f-string new in Python 3.6 ➡

>>> VARIABLE = 12
>>> s = f"cat /tmp/logall | sort -u | grep -v {VARIABLE}"
>>> s
'cat /tmp/logall | sort -u | grep -v 12'

Is there a way to in python 2.7? I cannot use 3 yet.

I found it:

>>> VARIABLE=12
>>> v_num_final_distinct_grid_disks_per_cell_and_dg = subprocess.check_output("cat /tmp/logall | sort -u | grep -v {}".format(VARIABLE), shell=True);
>>>
>>> print(v_num_final_distinct_grid_disks_per_cell_and_dg)
10

>>> VARIABLE=10
>>> v_num_final_distinct_grid_disks_per_cell_and_dg = subprocess.check_output("cat /tmp/logall | sort -u | grep -v {}".format(VARIABLE), shell=True);
>>> print(v_num_final_distinct_grid_disks_per_cell_and_dg)
12

>>>

4 alternatives:

import subprocess

# VARIABLE=12
# v_num_final_distinct_grid_disks_per_cell_and_dg = subprocess.check_output("cat /tmp/logall | sort -u | grep -v VARIABLE", shell=True)
# grep -v is invert match


def insecure(variable: str) -> str:
    return subprocess.check_output(f"cat /tmp/logall | sort -u | grep -v {variable}", shell=True, encoding="utf8")

    
def silly(variable: str) -> str:
    """
    Using PIPE to connect stdout with stdin of next process
    """
    cat_proc = subprocess.Popen(["cat", "/tmp/logall"], encoding="utf8", stdout=subprocess.PIPE)
    sort_proc = subprocess.Popen(["sort", "-u"], encoding="utf8", stdin=cat_proc.stdout, stdout=subprocess.PIPE)
    grep_proc = subprocess.Popen(["grep", "-v", variable], encoding="utf8", stdin=sort_proc.stdout, stdout=subprocess.PIPE)
    grep_proc.wait()
    return grep_proc.stdout.read()


def better(variable: str) -> str:
    lines = []
    with open("/tmp/logall") as fd:
        # fd is the the file-object
        # iterating over fd -> lines
        # creating a set from fd -> unique lines
        # sort set -> sorted unique lines
        for line in sorted(set(fd)):
            if variable not in line:
                lines.append(line.rstrip())
    return "\n".join(lines)


def better2(variable: str) -> list[str]:
    with open("/tmp/logall") as fd:
        return [
            line.rstrip()
            for line in sorted(set(fd))
            if variable not in line
        ]

better2 uses a list-comprehension to return all not matching lines as a list. The other functions do return the whole text as a single str.