如何在不使用重定向的情况下从文件读取Python脚本的命令行参数？

Question

I have a Python script that expects four command line arguments. Rather than typing out the values of these arguments in the command line every time I run the script, I want to store the values of the command line arguments in a file and have the Python script read those values from that file as command line arguments . For instance, if my desired command line arguments are

0  1  2  3

then the contents of a file called arguments_in_here.txt would be 0 1 2 3 . I would like some invocation on the command line like

$ python myscript.py < arguments_in_here.txt

to be interpreted as

$ python myscript.py 0 1 2 3

I already know that just using < doesn't work because I tried it out.

I can use xargs in the following way

$ cat arguments_in_here.txt | xargs python myscript.py

and achieve the desired result, but sort of in the Pythonic spirit I am wondering if there is a more direct and concise way to achieve what I want, without having to use a redirect.

Note: I could modify my Python script to take a file name as a command line argument, store my desired command line argument values in there, and then have my script pull the values from the file given to it on the command line, but I am wondering if there is any way for the Python script to read the command line arguments from a file through the command line.

Also note: If it ends up being relevant, I use Python 2.7 and tcsh

Answer 1

$ python myscript.py `cat arguments_in_here.txt`

这些是反引号，而不是常规的单引号。

Answer 2

If you use python myscript.py < arguments_here.txt than you need to read from stdin . Alternative you can use cat to get the arguments.

python myscript.py $(cat arguments_here.txt)

A short form for $(cat filename) is $(< filename) in bash.

Answer 3

inputs = list(sys.stdin)  # Get all of stdin
inputs = inputs[0]  # Get only the first line
inputs = inputs.split()  #  python myscript.py < 0123_arguments.txt => [0, 1, 2, 3]

Answer 4

My approach to this problem would be to use the argparse library in order to parse one command with the file name. Something like:

$ python program filepath

Then you can create a function that read the properties from your file and execute a function with those params