exec: add page (#2800)

pages/common/exec.md

@@ -0,0 +1,19 @@
+# exec
+
+> Replace the current process with another process.
+
+- Replace with the specified command using the current environment variables:
+
+`exec {{command -with -flags}}`
+
+- Replace with the specified command using initialized environment variables:
+
+`exec -c {{command -with -flags}}`
+
+- Replace with the specified command and login to the default shell:
+
+`exec -l {{command -with -flags}}`
+
+- Replace with the specified command and rename the process name:
+
+`exec -a {{process_name}} {{command -with -flags}}`