syslog(2) System Calls Manual syslog(2) syslog klogctl - / (libc -lc) #include /* SYS_* */ #include int syscall(SYS_syslog, int type, char *bufp, int size); /* The glibc interface */ #include int klogctl(int type, char *bufp, int size); : C syslog() syslogd(8) syslog(3) . syslog() printk() glibc klogctl(). LOG_BUF_LEN printk() ( ). LOG_BUF_LEN 4096 Linux 1.3.54 8192 Linux 2.1.113 16384 Linux 2.4.23/2.6 (CONFIG_LOG_BUF_SHIFT ). Linux 2.6.6 10 ( ). type . type. . SYSLOG_ACTION_CLOSE (0) . (NOP). SYSLOG_ACTION_OPEN (1) . (NOP). SYSLOG_ACTION_READ (2) . len bufp. . : . /proc/kmsg. SYSLOG_ACTION_READ_ALL (3) bufp. len ( ) " " ( 5 ). . SYSLOG_ACTION_READ_CLEAR (4) . type 3 " ". SYSLOG_ACTION_CLEAR (5) " ". bufp size. . 3 (SYSLOG_ACTION_READ_ALL) 4 (SYSLOG_ACTION_READ_CLEAR). 2 (SYSLOG_ACTION_READ) 9 (SYSLOG_ACTION_SIZE_UNREAD). SYSLOG_ACTION_CONSOLE_OFF (6) console_loglevel console_loglevel minimum_console_loglevel . Linux 2.6.32 console_loglevel minimum_console_loglevel. /proc/sys/kernel/printk . bufp size. SYSLOG_ACTION_CONSOLE_ON (7) SYSLOG_ACTION_CONSOLE_OFF console_loglevel . Linux 2.6.32 console_loglevel default_console_loglevel. /proc/sys/kernel/printk . bufp size. SYSLOG_ACTION_CONSOLE_LEVEL (8) console_loglevel size 1 8 (). size minimum_console_loglevel. . bufp. SYSLOG_ACTION_SIZE_UNREAD (9) ( Linux 2.4.10) 2 (SYSLOG_ACTION_READ). bufp size. SYSLOG_ACTION_SIZE_BUFFER (10) ( 2.6.6) . bufp size. 3 10 . 2.6.37 3 10 2.6.37 /proc/sys/kernel/dmesg_restrict 0. 2.6.37 " " CAP_SYS_ADMIN. 2.6.37 " " CAP_SYS_ADMIN ( ) CAP_SYSLOG (). /proc/sys/kernel/printk /proc/sys/kernel/printk printk() . : console_loglevel . DEFAULT_CONSOLE_LOGLEVEL (7) 4 "quiet" 10 "debug" 15 (10 15 8). console_loglevel ( 1-8) syslog() type 8. default_message_loglevel printk() . 2.6.38 4 (KERN_WARNING) 2.6.39 CONFIG_DEFAULT_MESSAGE_LOGLEVEL 4. minimum_console_loglevel console_loglevel . default_console_loglevel console_loglevel. printk() . default_message_loglevel. : KERN_EMERG 0 KERN_ALERT 1 KERN_CRIT 2 KERN_ERR 3 KERN_WARNING 4 KERN_NOTICE 5 KERN_INFO 6 KERN_DEBUG 7 printk() console_loglevel. type 2 3 4 syslog() . type 9 syslog() . type 10 syslog() . type 0 . -1 errno . EINVAL (: type type 2 3 4 buf NULL size type 8 level 1 8). ENOSYS syslog() CONFIG_PRINTK . EPERM console_loglevel ( : CAP_SYS_ADMIN CAP_SYSLOG). ERESTARTSYS . ( .) . . dmesg(1), syslog(3), capabilities(7) 3 . . : . 6.18 8 2026 syslog(2)