sock_diag – obtaining information about sockets Synopsis #include <linux/inet_diag.h> /* for IPv4 and IPv6 sockets */ #include <linux/sock_diag.h> #include <linux/unix_diag.h> /* for UNIX domain sockets */ #include <sys/socket.h> diag_socket = socket(AF_NETLINK, socket_type, NETLINK_SOCK_DIAG); Description The sock_diag netlink subsystem provides a mechanism for obtaining information about sockets of various address families from the kernel. This subsystem…
smokeping_upgrade – Notes on upgrading Smokeping Overview This document tries to list incompatible or otherwise user-visible changes in Smokeping versions, with instructions on how to fix any possible problems. It also sporadically mentions new features and the like. The document currently starts with changes from 1.34 to 1.37. If you run into problems with upgrading…
smokeping_master_slave – How to run multiple distributed instances of SmokePing Overview Normally smokeping probes run their tests from the host where smokeping runs to some target host and monitor the latency of the connection between the two. The Master/Slave concept enables all smokeping probes to run remotely. The use case for this is to measure…
smokeping_install – How to install SmokePing Overview This document explains how to setup SmokePing at your site. Description Prerequisites SmokePing does not stand alone. It relies on various other tools and services being present. Apart from a Unix OS and a working Perl installation you need the following components: RRDtool 1.2.x or later Smokeping uses…
smokeping_extend – Notes on extending Smokeping Overview This document is intended to guide prospective authors in writing new Smokeping probes. It mostly describes the interface between Smokeping and its probe modules. If it seems too complicated to understand, look at the existing modules for examples. Comments and proposed changes or additions are welcome. Please send…
signal – overview of signals Description Linux supports both POSIX reliable signals (hereinafter "standard signals") and POSIX real-time signals. Signal dispositions Each signal has a current disposition, which determines how the process behaves when it is delivered the signal. The entries in the "Action" column of the table below specify the default disposition for each…
signal-safety – async-signal-safe functions Description An async-signal-safe function is one that can be safely called from within a signal handler. Many functions are not async-signal-safe. In particular, nonreentrant functions are generally unsafe to call from a signal handler. The kinds of issues that render a function unsafe can be quickly understood when one considers the…
sigevent – structure for notification from asynchronous routines Synopsis #include <signal.h> union sigval { /* Data passed with notification */ int sival_int; /* Integer value */ void *sival_ptr; /* Pointer value */ }; struct sigevent { int sigev_notify; /* Notification method */ int sigev_signo; /* Notification signal */ union sigval sigev_value; /* Data passed with…
shm_overview – overview of POSIX shared memory Description The POSIX shared memory API allows processes to communicate information by sharing a region of memory. The interfaces employed in the API are: shm_open(3) Create and open a new object, or open an existing object. This is analogous to open(2). The call returns a file descriptor for…
session-keyring – session shared process keyring Description The session keyring is a keyring used to anchor keys on behalf of a process. It is typically created by pam_keyinit(8) when a user logs in and a link will be added that refers to the user-keyring(7). Optionally, PAM may revoke the session keyring on logout. (In typical…
session-end – event signalling session shutdown Synopsis session-end TYPE=TYPE Description The session-end event is generated by the Upstart init(8) daemon when running as a Session Init (where its pid is not 1) when requested to stop. The TYPE environment variable will be set to either shutdown when the Session Init has received the SIGTERM signal,…
semver – The semantic versioner for npm Usage $ npm install semver semver.valid(‘1.2.3’) // ‘1.2.3’ semver.valid(‘a.b.c’) // null semver.clean(‘ =v1.2.3 ‘) // ‘1.2.3’ semver.satisfies(‘1.2.3’, ‘1.x || >=2.5.0 || 5.0.0 – 7.2.3’) // true semver.gt(‘1.2.3’, ‘9.8.7’) // false semver.lt(‘1.2.3’, ‘9.8.7’) // true As a command-line utility: $ semver -h Usage: semver <version> [<version> […]] [-r <range>…
sem_overview – overview of POSIX semaphores Description POSIX semaphores allow processes and threads to synchronize their actions. A semaphore is an integer whose value is never allowed to fall below zero. Two operations can be performed on semaphores: increment the semaphore value by one (sem_post(3)); and decrement the semaphore value by one (sem_wait(3)). If the…
Xsecurity – X display access control Synopsis X provides mechanism for implementing many access control systems. The sample implementation includes six mechanisms: Host Access Simple host-based access control. MIT-MAGIC-COOKIE-1 Shared plain-text "cookies". XDM-AUTHORIZATION-1 Secure DES based private-keys. SUN-DES-1 Based on Sun’s secure rpc system. MIT-KERBEROS-5 Kerberos Version 5 user-to-user. Server Interpreted Server-dependent methods of access…
sd-readahead – Reference implementation of APIs for controlling boot-time read-ahead Synopsis #include "sd-readahead.h" Description sd-readahead.c and sd-readahead.h provide a reference implementation for APIs for controlling boot-time read-ahead, as implemented by the read-ahead subsystem of the systemd(1) init system. See sd_readahead(3) for more information about the function implemented. Notes This interface is provided by the reference…
sd-login – APIs for tracking logins Synopsis #include <systemd/sd-login.h> pkg-config –cflags –libs libsystemd-login Description sd-login.h provides APIs to introspect and monitor seat, login session and user status information on the local system. See m[blue]Multi-Seat on Linuxm[][1] for an introduction into multi-seat support on Linux, the background for this set of APIs. Note that these APIs…
sd-daemon – Reference implementation of APIs for new-style daemons Synopsis #include <systemd/sd-daemon.h> pkg-config –cflags –libs libsystemd-daemon Description sd-daemon.c and sd-daemon.h provide a reference implementation of various APIs for new-style daemons, as implemented by the systemd(1) init system. See sd_listen_fds(3), sd_notify(3), sd_booted(3), sd_is_fifo(3) for more information about the functions implemented. In addition to these functions a…
systemd-boot, sd-boot – A simple UEFI boot manager Description systemd-boot (short: sd-boot) is a simple UEFI boot manager. It provides a graphical menu to select the entry to boot and an editor for the kernel command line. systemd-boot supports systems with UEFI firmware only. systemd-boot loads boot entry information from the EFI system partition (ESP),…
sctp – SCTP protocol. Synopsis #include <sys/socket.h> #include <netinet/in.h> #include <netinet/sctp.h> sctp_socket = socket(PF_INET, SOCK_STREAM, IPPROTO_SCTP); sctp_socket = socket(PF_INET, SOCK_SEQPACKET, IPPROTO_SCTP); Description This is an implementation of the SCTP protocol as defined in RFC2960 and RFC3309. It is a message oriented, reliable transport protocol with direct support for multihoming that runs on top of ip(7),…
sched – overview of CPU scheduling Description Since Linux 2.6.23, the default scheduler is CFS, the "Completely Fair Scheduler". The CFS scheduler replaced the earlier "O(1)" scheduler. API summary Linux provides the following system calls for controlling the CPU scheduling behavior, policy, and priority of processes (or, more precisely, threads). nice(2) Set a new nice…