pexpect “no such file or directory” for a bash command that works

Question

sCMD = 'ssh user@host cat some/path | grep "Oct 31\|Oct 30"'
child = pexpect.spawn(sCMD)
try:
    child.expect("assword")
except pexpect.EOF:
    raise Exception("Cannot connect to host")
child.sendline(ssh_pass)
lData = [s.strip(' \n\r:') for s in child.readlines()]

lData[0] reads "No such file or directory"

if I change the first line to read:

sCMD = 'ssh user@host cat some/path'

Then lData contains all the lines from the file.

But if I execute the exact same command (with the grep) in a terminal it works fine - it returns the text I expect. No complaints.

Any idea why the command performs differently when executed via pexpect?

Answer 1

sCMD = 'ssh user@host \'cat some/path | grep "Oct 31\|Oct 30"\''

for some reason pexpect requires those extra single quotes.