chkconfig: add page (#2217)

pages/linux/chkconfig.md

@@ -0,0 +1,27 @@
+# chkconfig
+
+> Manage the runlevel of services on CentOS 6.
+
+- List services with runlevel:
+
+`chkconfig --list`
+
+- Show a service's runlevel:
+
+`chkconfig --list {{ntpd}}`
+
+- Enable service at boot:
+
+`chkconfig {{sshd}} on`
+
+- Enable service at boot for runlevels 2, 3, 4, and 5:
+
+`chkconfig --level {{2345}} {{sshd}} on`
+
+- Disable service at boot:
+
+`chkconfig {{ntpd}} off`
+
+- Disable service at boot for runlevel 3:
+
+`chkconfig --level {{3}} {{ntpd}} off`