M templates/thoughts.html → templates/thoughts.html

@@ -4,9 +4,10 @@ {{ template "nav" . }}
 <div id="main">  
 <h3>thoughts</h3>
 <h4>2023</h4>
+<li><a href="/thought/shell-tip-print-json-with-printf.html">shell tip: print json with printf</a></li>
+<li><a href="/thought/i-will-never-participate-in-weird-internet-caste-systems.html">i will never participate in weird internet caste systems</a></li>
 <li><a href="/thought/vore-a-new-rss-feed-reader.html">vore: a new rss feed reader</a></li>
 <li><a href="/thought/write-posix-shell.html">write posix shell</a></li>
-<li><a href="/thought/i-will-never-participate-in-weird-internet-caste-systems.html">i will never participate in weird internet caste systems</a></li>
 <h4>2022</h4>
 <li><a href="/thought/.io-domains-considered-harmful.html">.io domains considered harmful</a></li>
 <li><a href="/thought/drones-run-linux-free-software-isnt-enough.html">drones run linux: free software isn't enough</a></li>

A thought/shell-tip-print-json-with-printf.html

@@ -0,0 +1,78 @@ 
+shell tip: print json with printf
+2023-10-06
+
+i am commonly consulted when people are having strange issues with shell.
+
+one of the most common issues that shows up is when people try printing their
+json in shell.
+
+printing json might seem straightforward at first, just:
+
+    $ echo '{"name": "jes", "sign": "aquarius"}'
+    {"name": "jes", "sign": "aquarius"}
+
+but inevitably, variables show up:
+
+    $ echo '{"name": "$name", "sign": "$sign"}'
+    {"name": "$name", "sign": "$sign"} <-- this output is very broken
+
+at this point, the shell user realizes that they need double quotes in order
+to make variables interpolate properly.
+
+the user then commits one of two *cardinal* sins:
+
+sin 1: the eternal double-quote swamp
+
+    $ echo "{\"name\": \"$name\", \"sign\": \"aquarius\"}"
+    {"name": "jes", "sign": "aquarius"}
+
+if you write anything as ugly as the abomination above in shell, you are
+sending a clear signal that you do not care about yourself. you are condemning
+yourself to wade through the double-quote swamp for eternity.
+and you will deserve it.
+
+    '\"\"\"\"\"\""\""\"'\\""\"""\\""\""\"\\\"\""\""\"""\\""\\"
+       ^ a small portion of the eternal double-quote swamp ^
+
+sin 2: the long ugly HEREDOC
+
+    $ cat <<-EOF
+    {"name": "$name", "sign": "$sign"}
+    EOF
+    {"name": "jes", "sign": "aquarius"}
+
+the HEREDOC is more forgivable, but it takes up 2 unnecessary lines, and it's
+much harder to recall on-the-fly. and frankly, it looks pretty strange.
+
+and god forbid if you have to use a heredoc in an indented block.
+
+kiss your nice orderly indentation goodbye:
+
+    if blah; then
+        cat <<-EOF
+    {"name": "$name", "sign": "$sign"}
+    EOF
+    fi
+
+
+there is a better way! we just need to bust out our old dusty friend *printf*
+
+printf offers several advantages over echo:
+  - many languages (C, Go) have a printf equivalent, so it feels familiar
+  - printf behavior does not differ across systems (it is posix compliant)
+  - printf handles escape sequences (printf "hello\nworld\n")
+  - printf can trivially handle json
+
+witness, as we print the same json text using printf:
+
+    $ printf '{"name": "%s", "sign": "%s"}' "$name" "$sign"
+    {"name": "jes", "sign": "aquarius"}
+
+& there you have it! nice orderly json using an easy to remember command, with
+no-fuss variable injection built-in.
+
+i hope that this tip saves you some pain!
+
+
+love,
+  jes