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Test Your Knowledge in Computers #601
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Consider the Unix command sequence ps aux | grep -iv apache2 | wc -l This command will output the total number of apache2 processes running.
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machinectl(1) [centos man page]

MACHINECTL(1)							    machinectl							     MACHINECTL(1)

NAME
machinectl - Control the systemd machine manager SYNOPSIS
machinectl [OPTIONS...] {COMMAND} [NAME...] DESCRIPTION
machinectl may be used to introspect and control the state of the systemd(1) virtual machine and container registration manager systemd- machined.service(8). OPTIONS
The following options are understood: -h, --help Prints a short help text and exits. --version Prints a short version string and exits. -p, --property= When showing machine properties, limit the output to certain properties as specified by the argument. If not specified, all set properties are shown. The argument should be a property name, such as "Name". If specified more than once, all properties with the specified names are shown. -a, --all When showing machine properties, show all properties regardless of whether they are set or not. -l, --full Do not ellipsize process tree entries. --no-pager Do not pipe output into a pager. --no-ask-password Do not query the user for authentication for privileged operations. --kill-who= When used with kill-machine, choose which processes to kill. Must be one of leader, or all to select whether to kill only the leader process of the machine or all processes of the machine. If omitted, defaults to all. -s, --signal= When used with kill-machine, choose which signal to send to selected processes. Must be one of the well-known signal specifiers, such as SIGTERM, SIGINT or SIGSTOP. If omitted, defaults to SIGTERM. -H, --host Execute operation remotely. Specify a hostname, or username and hostname separated by "@", to connect to. This will use SSH to talk to the remote machine manager instance. -P, --privileged Acquire privileges via PolicyKit before executing the operation. The following commands are understood: list List currently running virtual machines and containers. status [ID...] Show terse runtime status information about one or more virtual machines and containers. This function is intended to generate human-readable output. If you are looking for computer-parsable output, use show instead. show [ID...] Show properties of one or more registered virtual machines or containers or the manager itself. If no argument is specified, properties of the manager will be shown. If an ID is specified, properties of this virtual machine or container are shown. By default, empty properties are suppressed. Use --all to show those too. To select specific properties to show, use --property=. This command is intended to be used whenever computer-parsable output is required. Use status if you are looking for formatted human-readable output. terminate [ID...] Terminates a virtual machine or container. This kills all processes of the virtual machine or container and deallocates all resources attached to that instance. kill [ID...] Send a signal to one or more processes of the virtual machine or container. This means processes as seen by the host, not the processes inside the virtual machine or container. Use --kill-who= to select which process to kill. Use --signal= to select the signal to send. EXIT STATUS
On success, 0 is returned, a non-zero failure code otherwise. ENVIRONMENT
$SYSTEMD_PAGER Pager to use when --no-pager is not given; overrides $PAGER. Setting this to an empty string or the value "cat" is equivalent to passing --no-pager. SEE ALSO
systemd-machined.service(8), systemd-logind.service(8), systemd.special(7). systemd 208 MACHINECTL(1)

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SYSTEMD-LOGINCTL(1)						 systemd-loginctl					       SYSTEMD-LOGINCTL(1)

NAME
systemd-loginctl - Control the systemd login manager SYNOPSIS
systemd-loginctl [OPTIONS...] {COMMAND} [NAME...] DESCRIPTION
systemd-loginctl may be used to introspect and control the state of the systemd(1) login manager. OPTIONS
The following options are understood: --help, -h Prints a short help text and exits. --version Prints a short version string and exits. --property=, -p When showing session/user/ properties, limit display to certain properties as specified as argument. If not specified all set properties are shown. The argument should be a property name, such as Sessions. If specified more than once all properties with the specified names are shown. --all, -a When showing unit/job/manager properties, show all properties regardless whether they are set or not. --no-pager Do not pipe output into a pager. --kill-who= When used with kill-session, choose which processes to kill. Must be one of leader, or all to select whether to kill only the leader process of the session or all processes of the session. If omitted defaults to all. --signal=, -s When used with kill-session or kill-user, choose which signal to send to selected processes. Must be one of the well known signal specifiers such as SIGTERM, SIGINT or SIGSTOP. If omitted defaults to SIGTERM. -H, --host Execute operation remotely. Specify a hostname, or username and hostname separated by @, to connect to. This will use SSH to talk to the remote login manager instance. -P, --privileged Acquire privileges via PolicyKit before executing the operation. The following commands are understood: list-sessions List current sessions. session-status [ID...] Show terse runtime status information about one or more sessions. This function is intended to generate human-readable output. If you are looking for computer-parsable output, use show-session instead. show-session [ID...] Show properties of one or more sessions or the manager itself. If no argument is specified properties of the manager will be shown. If a session ID is specified properties of the session is shown. By default, empty properties are suppressed. Use --all to show those too. To select specific properties to show use --property=. This command is intended to be used whenever computer-parsable output is required. Use session-status if you are looking for formatted human-readable output. activate [ID...] Activate one or more sessions. This brings one or more sessions into the foreground, if another session is currently in the foreground on the respective seat. lock-session [ID...], unlock-session [ID...] Activates/deactivates the screen lock on one or more sessions, if the session supports it. terminate-session [ID...] Terminates a session. This kills all processes of the session and deallocates all resources attached to the session. kill-session [ID...] Send a signal to one or more processes of the session. Use --kill-who= to select which process to kill. Use --signal= to select the signal to send. list-users List currently logged in users. user-status [USER...] Show terse runtime status information about one or more logged in users. This function is intended to generate human-readable output. If you are looking for computer-parsable output, use show-user instead. Users may be specified by their usernames or numeric user IDs. show-user [USER...] Show properties of one or more users or the manager itself. If no argument is specified properties of the manager will be shown. If a user is specified properties of the user is shown. By default, empty properties are suppressed. Use --all to show those too. To select specific properties to show use --property=. This command is intended to be used whenever computer-parsable output is required. Use user-status if you are looking for formatted human-readable output. enable-linger [USER...], disable-linger [USER...] Enable/disable user lingering for one or more users. If enabled for a specific user a user manager is spawned for him/her at boot, and kept around after logouts. This allows users who aren't logged in to run long-running services. terminate-user [USER...] Terminates all sessions of a user. This kills all processes of all sessions of the user and deallocates all runtime resources attached to the user. kill-user [USER...] Send a signal to all processes of a user. Use --signal= to select the signal to send. list-seats List currently available seats on the local system. seat-status [NAME...] Show terse runtime status information about one or more seats. This function is intended to generate human-readable output. If you are looking for computer-parsable output, use show-seat instead. show-seat [NAME...] Show properties of one or more seats or the manager itself. If no argument is specified properties of the manager will be shown. If a seat is specified properties of the seat are shown. By default, empty properties are suppressed. Use --all to show those too. To select specific properties to show use --property=. This command is intended to be used whenever computer-parsable output is required. Use seat-status if you are looking for formatted human-readable output. attach [NAME] [DEVICE...] Attach one or more devices to a seat. The devices should be specified via device paths in the /sys file system. To create a new seat attach at least one graphics card to a previously unused seat names. seat names may consist only of a-z, A-Z, 0-9, "-" and "_" and must be prefixed with "seat". To drop assignment of a device to a specific seat just reassign it to a different seat, or use flush-devices. flush-devices Removes all device assignments previously created with attach. After this call only automatically generated seats will remain and all seat hardware is assigned to them. terminate-seat [NAME...] Terminates all sessions on a seat. This kills all processes of all sessions on a seat and deallocates all runtime resources attached to them. EXIT STATUS
On success 0 is returned, a non-zero failure code otherwise. ENVIRONMENT
$SYSTEMD_PAGER Pager to use when --no-pager is not given; overrides $PAGER. Setting this to an empty string or the value cat is equivalent to passing --no-pager. SEE ALSO
systemd(1), systemctl(1), systemd-logind.conf(5) AUTHOR
Lennart Poettering <lennart@poettering.net> Developer systemd 10/07/2013 SYSTEMD-LOGINCTL(1)

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