halfway done with the nushell post.
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title = "Nushell first impressions"
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date = 2024-03-01T11:34:04-06:00
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draft = true
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+++
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:caution-caption: pass:[<span style="font-size: 2em">☠</span>]
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:important-caption: pass:[<span style="font-size: 2em">❗</span>]
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:note-caption: pass:[<span style="font-size: 2em">✏️</span>]
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:tip-caption: pass:[<span style="font-size: 2em">💡</span>]
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:warning-caption: pass:[<span style="font-size: 2em">⚠</span>]
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:toc:
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:toclevels: 6
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Ive been trying out a bunch of new shell utilites lately,
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switching up my shell, terminal multiplexer, and even experimenting with my editor.
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Today, Id like to focus on my experiments with my shell.
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== My old setup
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Before this, I had been using a minimal zsh setup for a long time,
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with only built in features and a handmade prompt.
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Zsh is a good shell, probably one of the best posix shells out there,
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and I still use it when a posix shell is needed.
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However, I got tired of the endless footguns that posix shell scripting imposes,
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easy to make errors around quoting, word splitting, and escaping,
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the sort of thing that makes https://www.shellcheck.net/[shellcheck] necessary.
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I played around with fish for a few days,
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but it had many of the same fundamental design choices, mainly, being 'stringly typed',
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that made posix shells such a displeasure to work with.
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== A Nu shell
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While googling around for alternative shells, I stumbled across https://www.nushell.sh/[nushell],
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a shell that claimed to work around structured data instead of just strings.
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This was *exactly* what I was looking for, and I installed it immediately.
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I decided to work with it for around a month,
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give myself enough time to really use it,
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see not only how it felt with ordinary usage,
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but to give myself time and opportunity to construct a few pipelines and scripts in it.
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All that said, the month is up, and ive been collecting examples,
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thoughts, and some criticisms along the way.
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== Piping structured data
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// show some examples of grouping, sorting, etc without endless invocations of `cut`.
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== Parsing non-nu tools
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// show parsing initcall_debug logs, and how it then lets one do analysis on it
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```
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[ 0.518096] calling prandom_reseed+0x0/0x40 @ 1
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[ 0.518119] initcall prandom_reseed+0x0/0x40 returned 0 after 12 usecs
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[ 0.518127] calling clk_debug_init+0x0/0x140 @ 1
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[ 0.531128] initcall clk_debug_init+0x0/0x140 returned 0 after 12659 usecs
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[ 0.531145] calling imx_amp_power_init+0x0/0x13c @ 1
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[ 0.531156] initcall imx_amp_power_init+0x0/0x13c returned 0 after 1 usecs
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[ 0.531175] calling deferred_probe_initcall+0x0/0x3c @ 1
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[ 0.532275] imx_thermal 2000000.aips-bus:tempmon: Automotive CPU temperature grade - max:125C critical:120C passive:115C
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[ 0.533166] pcm1753 pcm1753: Setting maximum volume limit of 226
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[ 0.535167] asoc-simple-card sound: PCM1753-HiFi <-> 2024000.esai mapping ok
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[ 0.536199] initcall deferred_probe_initcall+0x0/0x3c returned 0 after 4880 usecs
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[ 0.536217] calling pm_genpd_debug_init+0x0/0x70 @ 1
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[ 0.536249] initcall pm_genpd_debug_init+0x0/0x70 returned 0 after 20 usecs
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[ 0.536262] calling genpd_poweroff_unused+0x0/0x8c @ 1
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[ 0.536284] initcall genpd_poweroff_unused+0x0/0x8c returned 0 after 11 usecs
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[ 0.536296] calling gpio_keys_init+0x0/0x20 @ 1
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```
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{{<highlight nushell "linenos=false">}}
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open $file |
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lines |
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find '] initcall ' |
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parse -r '\[\s*(?<timestamp>\d+\.\d+)\] (?<message>.+) returned (?<return>\d+) after (?<delta>.+)' |
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update timestamp {into float} |
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update delta {str replace ' usecs' 'us'} |
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update delta {into duration} |
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update return {into int} |
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move delta --after timestamp
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{{</highlight>}}
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== Defining custom commands
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// show the basic syntax for custom commands
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=== Built in arg parsing?
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// show syntax for custom args, and how it leads to auto completion and help generation.
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== Error messages
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== Whats not there yet
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// explain some limitations, tools that assume the existence of a posix shell (esp files one is instructed to source)
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// also explain the limitations where nushell scripts cannot pass structured data, but are treated as external commands, therefore their usefullness in a pipeline is limited.
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164
content/posts/nushell.md
Normal file
164
content/posts/nushell.md
Normal file
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@ -0,0 +1,164 @@
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+++
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title = "Nushell first impressions"
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date = 2024-03-01T11:34:04-06:00
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draft = true
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+++
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Ive been trying out a bunch of new shell utilities lately,
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switching up my shell, terminal multiplexer, and even experimenting with my editor.
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Today, Id like to focus on my experiments with my shell.
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## My old setup
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Before this, I had been using a minimal zsh setup for a long time,
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with only built in features and a handmade prompt.
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Zsh is a good shell, probably one of the best posix shells out there,
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and I still use it when a posix shell is needed.
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However, I got tired of the endless footguns that posix shell scripting imposes,
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easy to make errors around quoting, word splitting, and escaping,
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the sort of thing that makes [shellcheck](https://www.shellcheck.net/) necessary.
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I played around with fish for a few days,
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but it had many of the same fundamental design choices, mainly, being 'stringly typed',
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that made posix shells such a displeasure to work with.
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## A Nu shell
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While googling around for alternative shells, I stumbled across [nushell](https://www.nushell.sh/),
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a shell that claimed to work around structured data instead of just strings.
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This was *exactly* what I was looking for, and I installed it immediately.
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I decided to work with it for around a month,
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give myself enough time to really use it,
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see not only how it felt with ordinary usage,
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but to give myself time and opportunity to construct a few pipelines and scripts in it.
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All that said, the month is up, and Ive been collecting examples,
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thoughts, and some criticisms along the way.
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## Piping structured data
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One of the core features of nushell is that commands return structured data,
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instead of plain strings.
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Pipelines can pass lists, records, or tables.
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Individual entries can be one of several built in datatypes,
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including rich datatypes like datetimes, durations, and filesizes.
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Nushell can also open many filetypes and turn them into nushell native datastructures to work with,
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including csv's, json, toml, yaml, xml, sqlite files, and even excel and libreoffice calc spreadsheets.
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Once you have your data in nushell datastructures,
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you can do all sorts of manipulations on it.
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It feels like an interesting mix of functional programming and SQL,
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but it actually works really, really well.
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You can sort, filter, and aggregate the data,
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use a SQL style join statement between two tables,
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and use functional programming patterns to manipulate tables.
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Some examples of things that nushell enables with this structured data passing
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through pipelines includes:
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{{<highlight sh>}}
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# show all files recurisively that were modified in the last week
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ls **/* | where modified > (
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# create timestamp from relative human readable string.
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'1 week ago' | into datetime
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)
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{{</highlight>}}
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{{<highlight sh>}}
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# show all executables in the current directory that are currently running.
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ps |
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# convert the name of the called process into a path
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update name {|process| (which $process.name).path.0?} |
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# join with the list of all files in the current directory, recursing down subdirectories.
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join (ls -f **/*) name
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{{</highlight>}}
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{{<highlight sh>}}
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# show all values in 1 csv but not in another
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open all_tasks.csv |
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# filter out tasks that cause the closure to return false
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filter { |task|
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not (
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# check if the task number is in the other csv.
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$task.number in (
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open tasks_done.csv |
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get 'task_number'
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)
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)
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}
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{{</highlight>}}
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All of these can be one liners, but have been broken up in order to insert
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explanatory comments.
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## Parsing non-nu tools
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But what if our tool/text file isnt in a format nushell understands?
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Thankfully, for most formats, parsing is relatively straightforward.
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Lets take this NGINX server log, for example (not a log of real traffic, just a
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sample log I found)
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{{<highlight text "linenostart=9184">}}
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135.125.217.54 - - [27/Mar/2023:12:57:44 +0000] "GET /.env HTTP/1.1" 404 197 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36"
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135.125.217.54 - - [27/Mar/2023:12:57:44 +0000] "POST / HTTP/1.1" 405 568 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.129 Safari/537.36"
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43.154.141.71 - - [27/Mar/2023:12:58:04 +0000] "HEAD /Core/Skin/Login.aspx HTTP/1.1" 404 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36"
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193.32.162.159 - - [27/Mar/2023:13:01:07 +0000] "GET / HTTP/1.1" 200 13 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46"
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193.32.162.159 - - [27/Mar/2023:13:01:18 +0000] "GET /dispatch.asp HTTP/1.1" 404 197 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46"
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{{</highlight>}}
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We can parse it into a nu table like so (each line has a comment explaining what
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it does, for those unfamiliar with the nushell language):
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{{<highlight sh>}}
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open access.log |
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# turn into a list of lines
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lines |
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# parse into a table
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parse '{ip} - {user} [{time}] "{request_type} {request}" {status} {bytes_sent} "{referrer}" "{user_agent}"' |
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# parse time into proper datetime
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update time {into datetime -f '%d/%b/%Y:%T %z'} |
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# parse into proper integer
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update bytes_sent {into int}
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{{</highlight>}}
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Now that we have it in nushell tables, we can bring all of nushells tools to
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bear on the data. We could, for example, plot a histogram of the most common
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ips, just by piping the whole thing into `histogram ip`. We could easily
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calculate the average bytes sent per request. We could group the records by the
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day or hour they happened, and analyze each of those groups independently. And
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we can do all of that after arbitrarily filtering, sorting, or otherwise
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transforming the table.
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While it would be a pretty long one liner if we decided to put it in a single
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line, its still quite easy and straightforward to write.
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Most log formats and command outputs are similarly straightforward.
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## Defining custom commands
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// show the basic syntax for custom commands
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### Built in arg parsing?
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// show syntax for custom args, and how it leads to auto completion and help generation.
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## Error messages
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## Whats not there yet
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Now, nushell is not finished yet.
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As I write, I am running version 0.91 of nu.
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Similar to fish, it not being a POSIX shell means that you still need to drop
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into bash or zsh in order to source env files in order to,
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for example, use a cross-compiling c/c++ sdk.
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(thankfully, python virtualenvs already come with a nu script for you to source,
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so doing python dev will not require you to launch a POSIX shell)
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Additionally, while you can write nu script files,
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invoking them from within nu treats them as external commands,
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meaning they take in and pass out plain text,
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rather than the structured data that you would get with a proper custom command
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or nu builtin.
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//explain the best workaround.
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@ -6,7 +6,7 @@ enableRobotsTXT = true
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[params]
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env = 'production'
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title = 'Mildly interesting'
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description = "Mildly interesting Things ive Done"
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description = "Mildly Interesting Writings"
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author = 'Gabe Venberg'
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DateFormat = "2006-1-2"
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defaultTheme = 'dark'
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@ -35,7 +35,7 @@ disableHLJS = true
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[params.homeInfoParams]
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Title = "Mildly Interesting"
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Content = """
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Mildly interesting things Ive done.
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Mildly interesting writings.
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"""
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[[params.socialIcons]]
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