Move pages under tldr, lint run.sh, update docs

tldr/osx/bc

@@ -0,0 +1,34 @@
+---
+syntax: markdown
+tags: [tldr, osx]
+source: https://github.com/tldr-pages/tldr.git
+---
+# bc
+
+> An arbitrary precision calculator language.
+> See also: `dc`.
+> More information: <https://keith.github.io/xcode-man-pages/bc.1.html>.
+
+- Start an interactive session:
+
+`bc`
+
+- Start an interactive session with the standard math library enabled:
+
+`bc --mathlib`
+
+- Calculate an expression:
+
+`bc --expression='{{5 / 3}}'`
+
+- Execute a script:
+
+`bc {{path/to/script.bc}}`
+
+- Calculate an expression with the specified scale:
+
+`bc --expression='scale = {{10}}; {{5 / 3}}'`
+
+- Calculate a sine/cosine/arctangent/natural logarithm/exponential function using `mathlib`:
+
+`bc --mathlib --expression='{{s|c|a|l|e}}({{1}})'`