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

tldr/entr

@@ -0,0 +1,25 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# entr
+
+> Run arbitrary commands when files change.
+> More information: <https://manned.org/entr>.
+
+- Rebuild with `make` if any file in any subdirectory changes:
+
+`{{ag -l}} | entr {{make}}`
+
+- Rebuild and test with `make` if any `.c` source files in the current directory change:
+
+`{{ls *.c}} | entr {{'make && make test'}}`
+
+- Send a `SIGTERM` to any previously spawned ruby subprocesses before executing `ruby main.rb`:
+
+`{{ls *.rb}} | entr -r {{ruby main.rb}}`
+
+- Run a command with the changed file (`/_`) as an argument:
+
+`{{ls *.sql}} | entr {{psql -f}} /_`