Commands tagged System Administration (11)

  • Run a file system check on your next boot.

    The empty file /forcefsck causes the file system check fsck to be run next time you boot up, after which it will be removed. This works too: sudo >/forcefsck


    38
    sudo touch /forcefsck
    johnraff · 2009-10-29 17:04:47 19
  • List all files opened by a particular command

    List all file opened by a particular command based on it's command name. Show Sample Output


    25
    lsof -c dhcpd
    d4n3sh · 2009-04-17 07:18:38 11
  • List files opened by a PID

    Lis all files opened by a particular process id. "PID" Show Sample Output


    6
    lsof -p 15857
    d4n3sh · 2009-04-17 07:16:03 5
  • Don't spam root. Log your cronjob output to syslog

    This command will log the output of your simple cronjobs to syslog, and syslog will take it from there. Works great for monitoring scripts which only produce simple output. Advantages: * This can be used by regular users, without modifying system files like /etc/syslog.conf * Reduce cron spam to root@localhost (Please stop spaming the sysadmins) * Uses common tools like syslog (and logrotate) so that you don't need to maintain yet another krufty logfile. * Still ensures that the output is logged somewhere, for posterity. Perhaps it's stored the secure, central syslog server, for example. * Seems to work fine on Ubuntu, CentOS, FreeBSD & MacOSX Show Sample Output


    6
    */5 * * * * root /usr/local/nagios/sbin/nsca_check_disk 2>&1 |/usr/bin/logger -t nsca_check_disk
    StefanLasiewski · 2010-07-02 00:47:05 8
  • Listing package man page, services, config files and related rpm of a file, in one alias

    Many times I give the same commands in loop to find informations about a file. I use this as an alias to summarize that informations in a single command. Now with variables! :D Show Sample Output


    2
    fileinfo() { RPMQF=$(rpm -qf $1); RPMQL=$(rpm -ql $RPMQF);echo "man page:";whatis $(basename $1); echo "Services:"; echo -e "$RPMQL\n"|grep -P "\.service";echo "Config files:";rpm -qc $RPMQF;echo "Provided by:" $RPMQF; }
    nnsense · 2015-05-11 16:46:01 13
  • turn off auto hard disc boot scanning for ext3


    1
    tune2fs -c -1 -i 0 /dev/VG0/data
    christian773 · 2010-05-29 08:20:35 4
  • create random numbers within range for conjob usage

    if you need to install cron jobs in a given time range. Show Sample Output


    1
    H=$(until ([ $i -le 6 -a $i -gt 0 -o $i -le 23 -a $i -gt 21 ] ); do i=$(date +%N | cut -c8-10); done ; echo $i) ; M=$(until [ $i -le 59 ]; do i=$(date +%N | cut -c8-10); done ; echo $i) ; echo $M $H \* \* \* backup-rsync-push.sh
    christian773 · 2010-05-29 08:42:43 7
  • Which .service related this file?

    I use this as an alias to get all .service files related a single installed file/conf (if it has services, of course). For rpm based systems ;) Show Sample Output


    1
    qf2s() { rpm -ql $(rpm -qf $1)|grep -P "\.service"; }
    nnsense · 2015-05-11 16:32:16 9
  • Manage "legacy" service run control links

    Change run control links from start "S" to stop "K" (kill) for whatever run levels in curly braces for a service called "myservice". NEWFN variable is for the new filename stored in the in-line shell. Use different list of run levels (rc*.d, rc{1,3,5}.d, etc.) and/or swap S with K in the command to change function of run control links. Show Sample Output


    0
    sudo find /etc/rc{1..5}.d -name S99myservice -type l -exec sh -c 'NEWFN=`echo {} | sed 's/S99/K99/'` ; mv -v {} $NEWFN' \;
    zoomgarden · 2010-01-03 00:56:57 6
  • manually set system date/time

    date MMDDhhmmYYYY date MMDDhhmm # example 27.12.1975 08:00 date 122708001975 Show Sample Output


    -1
    date MMDDhhmmYYYY
    christian773 · 2010-05-29 08:26:13 4
  • show system installation date


    -3
    tune2fs -l $(df -P / | tail -n1 | cut -d' ' -f1 ) | grep 'Filesystem created:'
    christian773 · 2010-05-29 08:15:25 6

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Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

check open ports without netstat or lsof

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Make vim open in tabs by default (save to .profile)
I always add this to my .profile rc so I can do things like: "vim *.c" and the files are opened in tabs.

Find Duplicate Files (based on MD5 hash) -- For Mac OS X
This works on Mac OS X using the `md5` command instead of `md5sum`, which works similarly, but has a different output format. Note that this only prints the name of the duplicates, not the original file. This is handy because you can add `| xargs rm` to the end of the command to delete all the duplicates while leaving the original.

Salvage a borked terminal
This works in some situations where 'reset' and the other alternatives don't.

Browse system RAM in a human readable form
This command lets you see and scroll through all of the strings that are stored in the RAM at any given time. Press space bar to scroll through to see more pages (or use the arrow keys etc). Sometimes if you don't save that file that you were working on or want to get back something you closed it can be found floating around in here! The awk command only shows lines that are longer than 20 characters (to avoid seeing lots of junk that probably isn't "human readable"). If you want to dump the whole thing to a file replace the final '| less' with '> memorydump'. This is great for searching through many times (and with the added bonus that it doesn't overwrite any memory...). Here's a neat example to show up conversations that were had in pidgin (will probably work after it has been closed)... $sudo cat /proc/kcore | strings | grep '([0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\})' (depending on sudo settings it might be best to run $sudo su first to get to a # prompt)

Listen YouTube radios streaming
Listen YouTube radios streaming. I use it on an alias to easily enter kinda flow state for study/programming.

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Most simple way to get a list of open ports

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