Invalid Char In Expression Awk, Python

I have a command that looks like this: ps v -p 2585 | awk '{if ($9 != '%MEM') {print $9}}' Now this runs fine in bash, it just takes the memory portion of whatever pid you give it

Solution 1:

You don't need to protect the awk commands from the shell when you're running it via popen (the arguments are already split into a list, so your whitespace is left alone).

cmd2 = ['awk', '{if ($9 != "%MEM") {print $9}}']

will work fine.

---

Note for future reference

Python has some nice ways of writing strings that avoid escaping like you tried to do here, for situations where you do need it:

'''In this string, I don't need to escape a single ' character,
   or even a new-line, because the string only ends
   when it gets three ' characters in a row like this:'''"""The same is true of double-quotes like this.
Of course, whitespace and both the ' and " quote characters
are safe in here."""

Solution 2:

When you run the command in bash, bash removes the single quotes and gives awk the first argument:

{if ($9 != "%MEM") {print $9}}

You are giving it single quotes, which you ought not do. You should just write:

cmd2 = ['awk', '{if ($9 != "%MEM") {print $9}}']