321–330 of 500 posts
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c = defaultdict(lambda: 42) b = defaultdict(lambda: c) a = defaultdict(lambda: b) a["a"]["b"]["c"] # --> 42
Okay fair, I deserve that. I assumed it was obvious I meant arbitrary depth. Also d["a"] and d["a"]["b"] aren't 42.
I have a hard time understanding any use case outside of such mocking.
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> But on the other side of that coin its alot easier in python to do a complex regular expression I am not sure I would agree. Sed fills this role quite nicely. cat README.md | grep # | tr '[:lower:] [:upper:]' | sed 's/something/something_else/'
Now do that again, but this time the regular expression is controlled by 2 command line params, one which gives it the substitution, the other one is a boolean switch that tells it whether to ignore case. And the script has to give a good error if the substitution isn't a valid regular expression. It should also give me a helptext for its command line options if I ask it with `-h, --h`. In python I can use `opt/argpa…
If I wanted to parse cli args I would use case on the input to mux out the args. I personally prefer writing cli interfaces this way (when using a scripting language).
while test $# -gt 0; do
case "$1" in
-f|--flag) shift; FLAG="$1";;
esac
shift
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Awk is awesome but saying it literally takes 1 hour to properly learn it is a bit overselling.
All you need to do is learn that cmd | awk '{ $5 }' will print out the 5th word as delimited by one or more whitespace characters. Regexes support this easily but are cumbersome to write on the command line.
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I really don't think so! If you have experience with any scripting, you can fully grok the fundamentals of awk in 1 hour. You might not memorize all the nuances, but you can establish the fundamentals to a degree that most things you would try to achieve would take just a few minutes of brushing up. For those that haven't taken the time yet, I think this is a good place to start: https://learnxinyminutes.com/docs/awk…
I feel like I do this every three years then proceed to never use it. Then I read a post on hn and think about how great it could be; rinse and repeat
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> - It may be useful to copy `$PWD` into a variable before changing directory Why not use pushd/popd instead?
pushd and popd are commands which change the current working directory. In contrast, variables like $PWD are expressions, which are far more flexible. For example, we can run commands like `diff "$OLD_PWD/foo" "$PWD/bar"` which reference multiple directories. Doing that with pushd/popd would be weird, e.g. `diff "$(popd; echo "$PWD/foo")" "$PWD/bar"`
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Shell and SQL make you 10x productive over any alternative. Nothing even comes close. I've seen people scrambling for 1 hours to write some data munging, then spend another 1 hour to run it through a thread pool to utilize those cores , while somebody comfortable is shell writes a parallelized one liner, rips through GBs of data, and delivers the answer in 15 minutes. What Python is to Java, Shell is to Python. It sp…
> getting the shell quoting hell right Shameless plug coming, it this has been a pain point for me too. I found the issue with quotes (in most languages, but particularly in Bash et al) is that the same character is used to close the quote as is used to open it.m. So in my own shell I added support to use parentheses as quotes in addition to the single and double quotation ASCII symbols. This then allows you to nest…
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There are three numbers in this industry: 0, 1 and infinity. Any other number - especially when stated as a rule, limitation, or law - is highly suspect.
0, 1, 3 and infinity
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I tried PowerShell, hated it. The idea of manipulating objects instead of text streams is interesting, and avoids most of the footguns sh/bash have, but you also lose in flexibility. One reason is that there are thousands of command line tools in the UNIX ecosystem that process text streams and are designed to work with shells like bash. You have much less options when you are processing PowerShell objects. Note: I t…
"You have much less options when you are processing PowerShell objects." There is simply no need for the kind of extensive text processing common in Linux because every command returns an object whose fields can be directly referenced. Combined with the ConvertTo-Json command this is incredibly powerful. Honestly it seems like you are attempting to do things in PowerShell the bash way instead of the PowerShell way. "…
I favor POSIX and dash over bash, because POSIX is more portable. If a shell script needs any kind of functionality beyond POSIX, then that's a good time to upgrade to a higher-structure programming language. Here's my related list of shell script tactics: http://github.com/sixarm/unix-shell-script-tactics
Do you even ran your code in place where bash wasn't available? I held thought like you... 10 years ago but that really doesn't happen and if it does, rest of it probably won't work either...