I recently ran into the following problem on an Apache 2.4 server, where after server reboot the service itself would no longer start.<\/p>\n
This was the error whenever I tried to start it:<\/p>\n
$ tail -f error.log\r\n[auth_digest:error] [pid 11716] (2)No such file or directory:\r\n AH01762: Failed to create shared memory segment on file \/run\/httpd\/authdigest_shm.11716\r\n[auth_digest:error] [pid 11716] (2)No such file or directory:\r\n AH01760: failed to initialize shm - all nonce-count checking, one-time nonces,\r\n and MD5-sess algorithm disabled\r\n<\/pre>\nSystemd reported the same problem;<\/p>\n
$ systemctl status -l httpd.service\r\n - httpd.service - The Apache HTTP Server\r\n Loaded: loaded (\/usr\/lib\/systemd\/system\/httpd.service; enabled; vendor preset: disabled)\r\n Active: failed (Result: exit-code) since ...\r\n<\/pre>\nThe cause is shown in the first error message:\u00a0Failed to create shared memory segment on file \/run\/httpd\/authdigest_shm.11716<\/strong>.<\/p>\n
If I traced this, I noticed the directory\u00a0
\/run\/httpd<\/code>\u00a0no longer existed. The simple fix in this case, was to re-create that missing directory.<\/p>\n$ mkdir \/run\/httpd\r\n$ chown root:httpd \/run\/httpd\r\n$ chmod 0710 \/run\/httpd\r\n<\/pre>\nThe directory should be owned by root and writeable for the root user. The Apache group (in my case,\u00a0
httpd<\/code>), needs executable rights to look into the directory.<\/p>\n<\/div>\n<\/p>\n
iven facility which allows non-dependent subsystems to be started, controlled, or stopped in parallel. Here we explain how to add a custom script to the systemd facility.<\/p>\n
1. Write And Debug The Custom Script<\/h2>\n
Typically a systemd script is written as a shell script. Begin by writing your custom script using the normal conventions. We will call our script my-custom-script.sh and is straightforward:<\/p>\n
\n#!\/bin\/sh\r\necho \"I am a custom script\" > \/var\/tmp\/script.out\r\necho \"The script was run at : `date`\" >> > \/var\/tmp\/script.out<\/pre>\n<\/div>\nThe script must be executable.<\/p>\n
\n<\/ins><\/ins><\/ins># chmod 0755 \/var\/tmp\/my-custom-script.sh<\/span><\/p>\n<\/div>\n
2. Describe The Custom Script To systemd<\/h2>\n
With the script written and tested manually, the script is ready to be described to the systemd system. To do this, a\u00a0[name].service<\/strong>\u00a0file is needed. The syntax uses the INI format commonly used for configuration files. Continuing our example, we need a my-custom-script.service file. The executable will run exactly once for each time the service is started. The service will not be started until the networking layer is up and stable.<\/p>\n
Create a new service unit file at \/etc\/systemd\/system\/my-custom-script.service with below content. The name of the service unit is user defined and can be any name of your choice.<\/p>\n
\n# This is my-custom-script.service, which describes the my-custom-script.sh file\r\n[Unit]\r\nDescription=This is executed on shutdown or reboot\r\nDefaultDependencies=no\r\nWants=network-pre.target # (if network is required before running the script)\r\nBefore=network-pre.target shutdown.target reboot.target halt.target # Defines the order in which units are stoped. #(REQUIRED)\r\n\r\n[Service]\r\nType=oneshot # enables specifying multiple custom commands that are then executed sequentially. (REQUIRED)\r\nRemainAfterExit=true # required by the oneshot setting (REQUIRED)\r\nEnvironment=ONE='one' \"TWO='2\" # you can set some environment variables, that may be necessary to pass as arguments\r\nExecStart=\/bin\/true # because is a shutdown script nothing is done when this service is started\r\nExecStop=\/bin\/bash \/var\/tmp\/my-custom-script.sh ${ONE} ${TWO} # < --*********** change to the script full path ************ (REQUIRED)\r\nTimeoutStopSec=1min 35s # Configures the time to wait for stop. \r\n\r\n[Install]\r\nWantedBy=multi-user.target # When this unit is enabled, the units listed in WantedBy gain a Want dependency on the unit. (REQUIRED)<\/pre>\n<\/div>\n3. Enable The Script For Future Reboots<\/h2>\n
Similar to the chkconfig from earlier versions, the service must be enabled. Since a new service was added, notify the systemd daemon to reconfigure itself:<\/p>\n
\n# systemctl enable my-custom-script.service\r\n# systemctl daemon-reload<\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"Apache 2.4 AH01762 & AH01760: failed to initialize shm (Shared Memory Segment) <\/p>\n
Mattias Geniar, Tuesday, January 12, 2016<\/p>\n
I recently ran into the following problem on an Apache 2.4 server, where after server reboot the service itself would no longer start.<\/p>\n
This was the error whenever I tried to start it:<\/p>\n
$ tail -f error.log […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7718"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7718"}],"version-history":[{"count":2,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7718\/revisions"}],"predecessor-version":[{"id":7720,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/7718\/revisions\/7720"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7718"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7718"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7718"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}