grep, awk and sed alternatives for python? [closed] - python-3.x

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os.system(r"grep -R 'Webpage\|Thumbnail' tmp | awk -F ' ' '{print $2}' | sed '1~2s/\(.*\)/]\[img]\1\[\/img]\[\/URL]/g ; N;s/\(.*\)\n\(.*\)/\2\1/ ; s/^/\[URL=/' | tr -d '[:space:]' > ./" + t + ".files/bbcode.txt")
What its doing, grep lines with Keywords in tmp > awk split at space delimiter to get everything after the keywords > sed add "[img]" at start and "[/img][/URL]" at the end of every line > sed add "[URL=" to start and "]" at the end of every second line > move all odd lines to beginning of all even lines > remove all spaces and merge into one big line.
Please can someone point me in the right direction to do this in python?

Answer 1

Here is a simple stab at a Python replacement.
grep -R will recursively search regular files in the destination directory. This can be replaced with os.walk('tmp'). Remember that the third result from os.walk is just the file names; you have to glue back the directory in front of each one.
Fields are generally numbered starting with 1 in the Unix command-line tools, while Python's indexing is zero-based. So the second field from the line is line.split(' ')[1], not line.split(' ')[2]
Without access to your files, I had to guess what the sed script is really receiving as input. I'm assuming that every second output is a "Webpage" one and every other is a "Thumbnail" one.
Tangentially, piping Awk to sed and tr is basically useless; Awk can do everything those two tools can do all by itself (though a nontrivial sed script might be hard to reimplement in Awk -- but this is not an example of that. 1~2 is a GNU sed extension so this was never very portable to begin with, and would be a lot easier to read and understand in Awk.). Conversely, splitting on a single space with Awk is kind of overkill; cut -d ' ' -f2 would be a more economical and succinct way to do that.
import os
with open(t + ".files/bbcode.txt", "w") as bbcode:
for root, dirs, files in os.walk('tmp'):
for file in files:
with open(os.path.join(root, file)) as lines:
idx = 0
for line in lines:
if 'Webpage' in line or 'Thumbnail' in line:
idx += 1
field = line.split(' ')[1]
if idx % 2 == 1:
thumb = field
next
bbcode.write(
'[URL=%s][img]%s[/img][/URL]' % (field, thumb))
The decision to collect all output on a single long line is dubious; could you perhaps be persuaded to add a final \n to the write format string?