I'd like to pass input from a shell command over to a python script in an alias that uses a shell command.
test.py:
import sys
print(sys.argv)
the alias
alias foo='echo $(python test.py $1)'
since $ python cd_alias_test.py hello would print all the args: ['test.py', 'hello']
I'd expect this alias to do the same. However its stdout is
['test.py'] hello
Which means that the input string is being passed to stdin and not the script's arguments.
How I achieve the intended effect?
alias test='echo $(python test.py $1)'
$1 is not defined in an alias, aliases aren't shell functions; they're just text replacement; so your test hello gets expanded to echo $(python test.py ) hello, which gets expanded to echo ['test.py'] hello.
If you want a shell function, write one! (and don't call your function or alias test, that name is already reserved for the logical evaluation thing in your shell).
function foo() { echo $(python test.py $1) }
foo hello
But one really has to wonder: Why not simply make test.py executable (e.g. chmod 755 test.py) and include the #!/usr/bin/env python3 first line in it? Then you can just run it directly:
./test.py hello darkness my old friend
echo $(thing) could/should just be thing -- otherwise there's a risk of echo interpreting the output of thing as switches it should care about, e.g. echo $(printf "%s" "-n hello") ; echo world
alias foo='python cd_alias_test.py $1', then the output for $ foo hello will be ['cd_alias_test.py', 'hello']
Commented
Jun 23, 2022 at 18:21
$1, because an alias gets expanded to its value as if you just typed that in. So, your foo hello looks like you typed in python cd_alias_test.py $1 hello and that gets expanded to python cd_alias_test.py hello before execution. There's really no magic here. Just your assumption about what an alias does being a bit wrong, it seems! An alias doesn't take "arguments". An alias simply doesn't "exist" as programming construct: it gets replaced by its value before anything gets defined, expanded…
Commented
Jun 23, 2022 at 18:23
Your question is confusingly worded, but I seems you just want to execute an alias passing a parameter to your script.
I think this is what you want.
alias runtest='python test.py'
As otherwise mentioned, shell functions can be preferable to aliases -- allowing for less trivial arg handling.
So in this example:
function runtest() { python test.py "$1" ; }
