/* vi: set sw=4 ts=4: */ /* * * dmesg - display/control kernel ring buffer. * * Copyright 2006 Rob Landley * Copyright 2006 Bernhard Reutner-Fischer * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config DMESG //config: bool "dmesg (3.7 kb)" //config: default y //config: select PLATFORM_LINUX //config: help //config: dmesg is used to examine or control the kernel ring buffer. When the //config: Linux kernel prints messages to the system log, they are stored in //config: the kernel ring buffer. You can use dmesg to print the kernel's ring //config: buffer, clear the kernel ring buffer, change the size of the kernel //config: ring buffer, and change the priority level at which kernel messages //config: are also logged to the system console. Enable this option if you //config: wish to enable the 'dmesg' utility. //config: //config:config FEATURE_DMESG_PRETTY //config: bool "Pretty output" //config: default y //config: depends on DMESG //config: help //config: If you wish to scrub the syslog level from the output, say 'Y' here. //config: The syslog level is a string prefixed to every line with the form //config: "<#>". //config: //config: With this option you will see: //config: # dmesg //config: Linux version 2.6.17.4 ..... //config: BIOS-provided physical RAM map: //config: BIOS-e820: 0000000000000000 - 000000000009f000 (usable) //config: //config: Without this option you will see: //config: # dmesg //config: <5>Linux version 2.6.17.4 ..... //config: <6>BIOS-provided physical RAM map: //config: <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable) //applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_DMESG) += dmesg.o //usage:#define dmesg_trivial_usage //usage: "[-c] [-n LEVEL] [-s SIZE]" //usage:#define dmesg_full_usage "\n\n" //usage: "Print or control the kernel ring buffer\n" //usage: "\n -c Clear ring buffer after printing" //usage: "\n -n LEVEL Set console logging level" //usage: "\n -s SIZE Buffer size" //usage: "\n -r Print raw message buffer" #include #include "libbb.h" int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int dmesg_main(int argc UNUSED_PARAM, char **argv) { int len, level; char *buf; unsigned opts; enum { OPT_c = 1 << 0, OPT_s = 1 << 1, OPT_n = 1 << 2, OPT_r = 1 << 3 }; opts = getopt32(argv, "cs:+n:+r", &len, &level); if (opts & OPT_n) { if (klogctl(8, NULL, (long) level)) bb_perror_msg_and_die("klogctl"); return EXIT_SUCCESS; } if (!(opts & OPT_s)) len = klogctl(10, NULL, 0); /* read ring buffer size */ if (len < 16*1024) len = 16*1024; if (len > 16*1024*1024) len = 16*1024*1024; buf = xmalloc(len); len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */ if (len < 0) bb_perror_msg_and_die("klogctl"); if (len == 0) return EXIT_SUCCESS; if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) { int last = '\n'; int in = 0; /* Skip <[0-9]+> at the start of lines */ while (1) { if (last == '\n' && buf[in] == '<') { while (buf[in++] != '>' && in < len) ; } else { last = buf[in++]; putchar(last); } if (in >= len) break; } /* Make sure we end with a newline */ if (last != '\n') bb_putchar('\n'); } else { full_write(STDOUT_FILENO, buf, len); if (buf[len-1] != '\n') bb_putchar('\n'); } if (ENABLE_FEATURE_CLEAN_UP) free(buf); return EXIT_SUCCESS; }