Posted by & filed under Linux, RedHat.

With updates going on in the last couple of months for various packages, such as OpenSSL and GLibC which have fixed a number of important security vulnerabilities, I thought I might share a one liner that might save you one day.

sudo lsof -n | grep -v \#prelink\# | grep -e '\.so' | grep -e DEL | grep -e lib | grep -v ^init | sed -re 's|^([^0-9]*)\s*([0-9]*)[^/]*(\/.*)$|\1 (\2) \3|' | sort -u

Running lsof will list all of the currently opened files from processes running on your system. -n will stop lsof from resolving hostnames for processes that have opened network ports to different processes (such as your webserver, mail server etc)

Running grep a couple of times will ensure that we find all the processes that have loaded a shared binary that has been deleted.

Note that the “init” process has been excluded. This is done on purpose. init can not be restarted without rebooting or otherwise killing the system.

The sed magic will show a list of all the processes and their PID’s, along with the library that was deleted that triggered it being listed as an application that should be restarted.

tim@srv215.production [~]# REGEX='^([^0-9]*)\s*([0-9]*)[^/]*(\/.*)$|\1 (\2) \3'
tim@srv215.production [~]# sudo lsof -n | grep -v \#prelink\#  \
                            | grep -e '\.so' | grep -e DEL | grep -e lib \
                            | grep -v ^init \
                            | sed -re "s|$REXEG|" | sort -u
auditd      (1802) /lib64/ld-2.12.so
auditd      (1802) /lib64/libc-2.12.so
auditd      (1802) /lib64/libm-2.12.so
auditd      (1802) /lib64/libnsl-2.12.so
auditd      (1802) /lib64/libnss_files-2.12.so
auditd      (1802) /lib64/libpthread-2.12.so
auditd      (1802) /lib64/librt-2.12.so

Note that this will not work if the application is dynamically loaded (for example using dlopen(3)) or if the application is statically linked.

2 Responses to “Checking what processes need to be restarted after a system upgrade”

  1. Harald Hoyer

    Note that the “init” process has been excluded. This is done on purpose. init can not be restarted without rebooting or otherwise killing the system.

    Well, systemd can re-execute itself:
    # systemctl daemon-reexec

  2. Tim Groeneveld

    Yes, but you do need to be careful about this. init (or more specifically, PID 1) is special. If init fails to restart for some reason, your machine will kernel panic, making a scheduled downtime much more preferable when updating init, vs. just re-exec’ing the daemon.

    However your point is still quite valid!

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