Use xonsh to loop over files with ls - xonsh

Question

I want to use xonsh to bzip several files in a directory. I first attempt this with the following:
$ ls
table_aa.csv table_amgn.csv table_csco.csv table_esrx.csv table_hal.csv table_jbl.csv table_pcg.csv table_zmh.csv
table_aapl.csv table_amzn.csv table_d.csv table_gas.csv table_hp.csv table_jpm.csv table_usb.csv
$ for fn in ls:
.. bzip2 fn
..
NameError: name 'ls' is not defined
OK, so I use $() explicitly
$ for fn in $(ls).split():
. bzip2 fn
bzip2: Can't open input file fn: No such file or directory.
bzip2: Can't open input file fn: No such file or directory.
Is there a better way to do this?
$ xonsh --version
('xonsh/0.3.4',)

Answer 1

You are very close with the second example. The only thing to note is that fn is a Python variable name, so you have to use #() to pass it to a subprocess:
$ for fn in $(ls).split():
. bzip2 #(fn)
Also, on v0.3.4, you could use regex globbing instead of ls,
$ for fn in `.*`:
. bzip2 #(fn)
And at least on master, you can now iterate through !() line-by-line, which means that the following will also work if you are wedded to ls:
$ for fn in !(ls):
. bzip2 #(fn)

Answer 2

Using ls:
for fn in !(ls):
print(fn.rstrip())
Using globs (available in regex, shell, and path varieties):
for fn in g`*`:
print(fn)
Using Python APIs (see the os, glob, or pathlib modules):
import os
for fn in os.listdir():
print(fn)