Title: Port of the week: checkrestart
       Author: Solène
       Date: 02 March 2021
       Tags: openbsd portoftheweek
       Description: 
       
       # Introduction
       
       This article features the very useful program "checkrestart" which is
       OpenBSD specific.  The purpose of checkrestart is to display which
       programs and their according PID for which the binaries doesn't exist
       anymore.
       
       Why would their binary be absent? The obvious case is that the program
       was removed, but what it is really good at, is when you upgrade a
       package with running binaries, the old binary is deleted and the new
       binary installed.  In that case, you will have to stop all the running
       binaries and restart them. Hence the name "checkrestart".
       
       # Installation
       
       Installing it is as simple as running pkg_add checkrestart
       
       # Usage
       
       This is simple too, when you run checkrestart, you will have a list of
       PID numbers with the binary name.
       
       For example, on my system, checkrestart gives me information about what
       programs got updated that I should restart to run the new binary.
       
       ```
       69575        lagrange
       16033        lagrange
       9664        lagrange
       77211        dhcpleased
       6134        dhcpleased
       21860        dhcpleased
       ```
       
       # Real world usage
       
       If you run OpenBSD -stable, you will want to use checkrestart after
       running pkg_add -u.  After a package update, most often related to
       daemons, you will have to restart the related services.
       
       On my server, in my daily script updating packages and running
       syspatch, I use it to automatically restart some services.
       
       ```
       checkrestart | grep php && rcctl restart php-fpm
       checkrestart | grep postgres && rcctl restart postgresql
       checkrestart | grep nginx && rcctl restart nginx
       ```
       
       # Other Operating System
       
       I've been told that checkrestart is also available on FreeBSD as a
       package!  The output may differ but the use is the same.
       
       On Linux, a similar tool exists under the name "needrestart", at least
       on Debian and Gentoo.