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linux command pipe with python "-c" flag

I am trying to do a string printing with python -c flag, e.g.
python3 -c "print('Hello World')"
So now I wanna substitute an argument with pipe, e.g. echo "Hello World" | python3 -c "print($1)"
the pipe is to take output from previous command and take it as input to next command, if I am not wrong, this is possible? But I think I got syntax error which I cannot find any source of this
I also bumped into question previously asked, but the solution required python imports and .py file depends on how we run this, I understand but I just wanna get it in a line of command in linux shell

If your input is always single line then you should be able to harness input function for example
echo "Hello World" | python3 -c "print(input().upper())"
would output
HELLO WORLD

Printing .py file output in command line

I am trying to access a python function from the command line, and I would like to write such a command that will print the output in the terminal. The below doesn't work. What could I change?
python -c 'from laser import Laser; laser = Laser();l = laser.embed_sentences("hello", lang = "en").shape == (1, 1024); print(l)'

(base) ~ % python -c 'print("hello, world")'
hello, world
Printing works fine for me when running python through python -c. Are you sure your terminal isn't truncating your output by omitting the last (and in this case, only) line? You could try creating a single line file (no newline at the end) and then running cat [filename] (which is how I sometimes discover that my terminal is doing this)

-c cmd : program passed in as string (terminates option list)
That is the correct flag to be used. This must be a CLI config issue. Or the script is taking longer than you are expecting to run and it appears no output is generated.
Does python -c 'print("hello")' work?

determine file type of a file without extension

I want to use pygmentize to highlight some script files (python/bash/...) without extension. But pygmentize requires me to specify the lexer using -l. It does not automatically identify the file type from the content.
I have the following options at hand, but none of them work now:
use file -b --mime-type. But this command output x-python and x-shellscript instead of python and bash and I don't know the rules
use vim -e -c 'echo &ft|q' the_file. For any file with or without file extension, vim has a mechanism to guess the file type. But it doesn't work. Since the output goes to the vim window and disappears after q.
What can I do?
#Samborski's method works fine in normal case but it does not work in python subprocess.check_output since the pts is not allocated. If you use nvim, you can use this more straightforward way:
HOME=_ nvim --headless -es file <<EOF
call writefile([&ft], "/dev/stdout")
EOF

You can use vim this way:
vim -c ':silent execute ":!echo " . &ft . " > /dev/stdout"' -c ':q!' the_file
It simply constructs command to run in the shell as a string concatenation.

python 2.3 how to run a piped command

I want to run a command like this
grep -w 1 pattern <(tail -f mylogfile.log)
basically from a python script i want to monitor a log file for a specific string and continue with the python script as soon as i found that.
I am using os.system(), but that is hanging. The same command in bash works good.
I have a very old version of python (v2.3) and so don't have sub-process module.
do we have a way to acheive this

In Python 2.3, you need to use subprocess from SVN
import subprocess
import shlex
subprocess.call(shlex.split("/bin/bash -c 'grep -w 1 pattern <(tail -f mylogfile.log)'"))
To be explicit, you need to install it from the SVN link above.
You need to call this with /bin/bash -c due to the shell redirection you're using
EDIT
If you want to solve this with os.system(), just wrap the command in /bin/bash -c since you're using shell redirection...
os.system("/bin/bash -c 'grep -w 1 pattern <(tail -f mylogfile.log)'")

First of all, the command i think you should be using is grep -w -m 1 'pattern' <(tail -f in)
For executing commands in python, use the Popen constructor from the subprocess module. Read more at
http://docs.python.org/library/subprocess.html

If I understand correctly, you want to send the output to python like this -
tail -f mylogfile.log | grep -w 1 pattern | python yourscript.py
i.e., read all updates to the log file, and send matching lines to your script.
To read from standard input, you can use the file-like object: sys.stdin.
So your script would look like
import sys
for line in sys.stdin.readlines():
#process each line here.

Execute bash script from URL using python

Assume I have a file at http://mysite.com/myscript.sh that contains:
#!/bin/bash
echo "Hello $1"
From the command line, I can execute my script (without downloading it) using the following command:
bash <(curl -s http://mysite.com/myscript.sh) World
Now, instead of executing the above command from the command line, I want to execute it from a python script. I tried doing the following:
import os
os.system('bash <(curl -s http://mysite.com/myscript.sh) World')
...but I get the following error:
sh: -c: line 0: syntax error near unexpected token `('
How do I make this execute correctly in python?

Evidently, os.system runs its command through /bin/sh, which usually causes whichever shell it's linked to to drop to a compatibility mode that doesn't include the <(...) construction. You can get around it by either storing the result in a temporary file or using another level of shell. Ugly, but it works.
os.system('bash -c "bash <(curl -s http://mysite.com/myscript.sh) World"')

There is a libcurl for python so you don't have to go the way around to command line behaviour. Here's the function list that should really do it - have never run remote scripts myself though. If you need installing the python binding, the instructions are here.
import curl