I was doing a 24 hour code-a-thon and had to reboot numerous times and was wondering if there was a way to tell exactly how many the computer was rebooted or crashed.
Way to tell how many times the computer has rebooted in a 24 hour period
crashlogsreboot
Related Solutions
You can try the following bash script from this answer from ServerFault.
#!/bin/bash
LAST_KERNEL=$(rpm -q --last kernel | perl -pe 's/^kernel-(\S+).*/$1/' | head -1)
CURRENT_KERNEL=$(uname -r)
test $LAST_KERNEL = $CURRENT_KERNEL || echo REBOOT
Probably the easiest way to do this would be to use syslogd's debug switch, -d. You can invoke syslogd manually like so.
First disable any currently running syslogd:
$ sudo service syslogd stop
Then run it manually with the following switches:
$ sudo syslogd -d -f /etc/syslog.conf
Example
I don't have a working syslogd accessible but it would be very similar to rsyslogd. Here I'm invoking rsyslogd:
$ sudo rsyslogd -d -f /etc/rsyslog.conf
1647.845869757:7fab7df4b720: rsyslogd 4.6.3 startup, compatibility mode 0, module path ''
1647.846009627:7fab7df4b720: caller requested object 'net', not found (iRet -3003)
1647.846026890:7fab7df4b720: Requested to load module 'lmnet'
1647.846035733:7fab7df4b720: loading module '/lib64/rsyslog/lmnet.so'
1647.846155408:7fab7df4b720: module of type 2 being loaded.
1647.846167849:7fab7df4b720: source file conf.c requested reference for module 'lmnet', reference count now 1
1647.846178301:7fab7df4b720: rsyslog runtime initialized, version 4.6.3, current users 1
1647.846196912:7fab7df4b720: source file syslogd.c requested reference for module 'lmnet', reference count now 2
1647.848016526:7fab7df4b720: module of type 1 being loaded.
Testing
You can then use the command line tool logger to simulate messages of various types to syslogd. Again here I'm using rsyslogd as a stand in so the messaging will be different but the effect is still the same with either one.
Sending a test message
$ logger -t testmsg "hello world."Results
2439.368194624:7f461fee9700: Message from UNIX socket: #3 2439.368226046:7f461fee9700: logmsg: flags 4, from 'grinchy', msg Aug 20 03:07:19 testmsg: hello world. 2439.368234458:7f461fee9700: Message has legacy syslog format. 2439.368247194:7f461fee9700: main Q: entry added, size now 1 entries 2439.368257698:7f461fee9700: wtpAdviseMaxWorkers signals busy 2439.368271525:7f461fee9700: main Q: EnqueueMsg advised worker start 2439.368283031:7f461fee9700: --------imuxsock calling select, active file descriptors (max 3): 3 2439.368305014:7f46206ea700: main Q: entry deleted, state 0, size now 0 entries 2439.368329151:7f46206ea700: testing filter, f_pmask 127 2439.368340032:7f46206ea700: Called action, logging to builtin-file 2439.368354849:7f46206ea700: file to log to: /var/log/messages 2439.368361837:7f46206ea700: doWrite, pData->pStrm 0x7f462480a310, lenBuf 46 2439.368370439:7f46206ea700: strm 0x7f462480a310: file 5(messages) flush, buflen 46 2439.368413234:7f46206ea700: strm 0x7f462480a310: file 5 write wrote 46 bytes 2439.368424063:7f46206ea700: testing filter, f_pmask 0 2439.368431098:7f46206ea700: testing filter, f_pmask 0 2439.368437738:7f46206ea700: testing filter, f_pmask 0 2439.368444401:7f46206ea700: testing filter, f_pmask 1 2439.368450861:7f46206ea700: testing filter, f_pmask 0 2439.368457433:7f46206ea700: testing filter, f_pmask 0 2439.368464826:7f46206ea700: main Q:Reg/w0: worker IDLE, waiting for work.Log file's message
Aug 20 03:07:12 grinchy testmsg: hello world.
Another Example
Sample message
$ logger -p daemon.warn "this is only a test."Results
2008.317255462:7f3d13a95700: Message from UNIX socket: #3 2008.317287162:7f3d13a95700: logmsg: flags 4, from 'grinchy', msg Aug 20 03:00:08 saml: this is only a test. 2008.317295844:7f3d13a95700: Message has legacy syslog format. 2008.317307482:7f3d13a95700: main Q: entry added, size now 1 entries 2008.317317586:7f3d13a95700: wtpAdviseMaxWorkers signals busy 2008.317328948:7f3d13a95700: main Q: EnqueueMsg advised worker start 2008.317339316:7f3d13a95700: --------imuxsock calling select, active file descriptors (max 3): 3 2008.317362187:7f3d14296700: main Q: entry deleted, state 0, size now 0 entries 2008.317375008:7f3d14296700: testing filter, f_pmask 127 2008.317386832:7f3d14296700: Called action, logging to builtin-file 2008.317401184:7f3d14296700: file to log to: /var/log/messages 2008.317409775:7f3d14296700: doWrite, pData->pStrm 0x7f3d17506310, lenBuf 51 2008.317418935:7f3d14296700: strm 0x7f3d17506310: file 5(messages) flush, buflen 51 2008.317454814:7f3d14296700: strm 0x7f3d17506310: file 5 write wrote 51 bytes 2008.317466838:7f3d14296700: testing filter, f_pmask 0 2008.317474391:7f3d14296700: testing filter, f_pmask 0 2008.317481448:7f3d14296700: testing filter, f_pmask 0 2008.317488503:7f3d14296700: testing filter, f_pmask 1 2008.317495259:7f3d14296700: testing filter, f_pmask 0 2008.317502407:7f3d14296700: testing filter, f_pmask 0 2008.317509079:7f3d14296700: main Q:Reg/w0: worker IDLE, waiting for work.This line contains our message
2008.317287162:7f3d13a95700: logmsg: flags 4, from 'grinchy', msg Aug 20 03:00:08 saml: this is only a test.
When you're done, simply Ctrl + C to terminate it.
Best Answer
System reboots are usually logged in the binary file
/var/log/wtmp. The easiest way to read that file is using thelastcommand which prints lines like this for every reboot:so if you issue
last reboot, you'll get a list of all reboots logged to yourwtmpfile.