Commands by tyzbit (10)

  • Get the total RESIDENT memory used by processes of a specific name. This means this is the MINIMUM used by a process, but some memory could be paged out to swap. Show Sample Output


    0
    pids=$(pidof chrome); for p in ${pids[@]}; do cat /proc/$p/status | grep -i vmrss | awk '{print $2}'; done | while read m; do let t=$t+$m; echo $t; done | echo "$(tail -n 1) kB"
    tyzbit · 2018-04-08 16:43:35 1
  • simple jq one-liner to convert from configmaps to secrets (which require the values to be base64 encoded). To automatically pull the config map, convert it, and re-upload the corresponding secret: kubectl get --export -o json cm [configmap name] | jq 'with_entries(if .key == "data" then .value=(.value | to_entries | map( { (.key): (.value|@base64) } ) | add ) elif .key == "kind" then .value="Secret" else . end)' > secret.json; kubectl create -f secret.json Show Sample Output


    0
    cat configmap.json | jq 'with_entries(if .key == "data" then .value=(.value | to_entries | map( { (.key): (.value|@base64) } ) | add ) elif .key == "kind" then .value="Secret" else . end)'
    tyzbit · 2017-12-11 19:18:25 0
  • This is a bit of a bash hack to catch STDERR and append a log level to it. So for example, if your script has pseudo loglevels like so: echo "INFO - finding files" [ -f ${files} ] || echo "WARN - no files found" Any subcommands that write to STDERR will screw that up Adding 2> >(fb=$(dd bs=1 count=1 2>/dev/null | od -t o1 -A n); [ "$fb" ] && err=$(printf "\\${fb# }"; cat) && echo "ERROR - $err") to the command does the following: 2> Redirect STDERR >( Spawn a subshell (STDERR is then redirected to the file descriptor for this subshell) fb=$(....) get the first byte of input [ "$fb" ] test if there's a first byte && err=$(printf....) save the output to the $err variable && echo "ERROR - $err" append your pseudo loglevel and the error message Heavily borrowed from https://unix.stackexchange.com/questions/33049/check-if-pipe-is-empty-and-run-a-command-on-the-data-if-it-isnt Show Sample Output


    0
    [command] 2> >(fb=$(dd bs=1 count=1 2>/dev/null | od -t o1 -A n); [ "$fb" ] && err=$(printf "\\${fb# }"; cat) && echo "ERROR - $err")
    tyzbit · 2017-10-16 22:22:42 1
  • Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.


    15
    exec 5<>/dev/tcp/time.nist.gov/13; cat <&5 & cat >&5; exec 5>&-
    tyzbit · 2015-07-30 21:12:38 9
  • Most distributions alias cp to 'cp -i', which means when you attempt to copy into a directory that already contains the file, cp will prompt to overwrite. A great default to have, but when you mean to overwrite thousands of files, you don't want to sit there hitting [y] then [enter] thousands of times. Enter the backslash. It runs the command unaliased, so as in the example, cp will happily overwrite existing files much in the way mv works. Show Sample Output


    1
    \[command]
    tyzbit · 2015-01-15 18:31:50 0
  • Use this command to watch apache access logs in real time to see what pages are getting hit. Show Sample Output


    0
    tail -f access_log | awk '{print $1 , $12}'
    tyzbit · 2014-12-24 14:15:52 1
  • This is not exhaustive but after checking /etc/cron* is a good way to see if there are any other jobs any users may have set. Note: this is a repost from a comment "flatcap" made on http://www.commandlinefu.com/commands/view/3726/print-crontab-entries-for-all-the-users-that-actually-have-a-crontab#comment, for which I am grateful and I take no credit.


    0
    for USER in /var/spool/cron/*; do echo "--- crontab for $USER ---"; cat "$USER"; done
    tyzbit · 2014-12-11 19:48:46 1
  • This checks the system load every second and if it's over a certain threshold (.8 in this example), it spits out the date, system loads and top 4 processes sorted by CPU. Additionally, the \a in the first echo creates an audible bell.


    0
    while sleep 1; do if [ $(echo "$(cat /proc/loadavg | cut -d' ' -f1) > .8 " | bc) -gt 0 ]; then echo -e "\n\a"$(date)" \e[5m"$(cat /proc/loadavg)"\e[0m"; ps aux --sort=-%cpu|head -n 5; fi; done
    tyzbit · 2014-12-08 15:44:40 0
  • Wakes up a computer on your LAN with a Wake-On-LAN packet. MAC Address must match the NIC MAC, computer must have WOL enabled in the BIOS. Show Sample Output


    0
    wakeonlan 00:00:DE:AD:BE:EF
    tyzbit · 2014-06-13 16:16:33 0
  • Use this command to watch video files on the terminal using VLC. prerequisite: VLC and cvlc sudo apt-get install vlc cvlc Show Sample Output


    0
    cvlc /path/to/file.avi -V caca
    tyzbit · 2014-06-13 16:10:36 0

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Alias TAIL for automatic smart output
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Let keyboard LED blink

Save a file you edited in vim without the needed permissions (no echo)
Write a file you edited in Vim but that you do not have the permissions to write to (unless you use sudo.) Same as #1204 but without the echo to stdout that I find annoying.

C function manual

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Produce a pseudo random password with given length in base 64
Don't copy trailing '=' or use head -c to limit to desired length.

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"


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