Commands by UnixNeko (4)

  • Check if a machine is online

    PING parameters c 1 limits to 1 pinging attempt q makes the command quiet (or silent mode) /dev/null 2>&1 is to remove the display && echo ONLINE is executed if previous command is successful (return value 0) || echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself). I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done. Asking for the machine name or IP Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).


    9
    ping -c 1 -q MACHINE_IP_OR_NAME >/dev/null 2>&1 && echo ONLINE || echo OFFLINE
    UnixNeko · 2012-02-09 06:30:55 7
  • Extract a .gz file with privilege

    Extracting .gz files and placing the output in another directory in one command line is convenient thing. I just followed some how-to to install Nagios on Ubuntu Lucid Lynx but they give the method to install from archives. I wished to install from the repository. If you do so some files are missing. I've not tested yet but this is an example command line I did to extract sudo sh -c 'gunzip -c /usr/share/doc/nagios3-common/examples/template-object/templates.cfg.gz > /etc/nagios3/objects/templates.cfg' We need privilege to write the destination file. Show Sample Output


    0
    sudo sh -c 'gunzip -c source.gz > destination'
    UnixNeko · 2011-07-05 23:51:01 1
  • Rip CD

    Can be useful to rip a CD. Show Sample Output


    -1
    ripit -c 0 --outputdir $1 --nosubmission
    UnixNeko · 2011-06-12 12:29:26 0
  • Reload gnome-panel

    I have some problems with gnome panel which does not load completely leaving me without the actual GUI. This commands helps to kill the gnome-panel process then it should be relaunch automatically.


    -2
    pgrep -lf gnome-panel | awk '{if ($2=="gnome-panel") print $1}' | xargs kill -9
    UnixNeko · 2011-06-12 12:23:27 2

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Speed up launch of liferea
If you use liferea frequently, you will see obvious speedup after you executed this command.

See a full list of compiler defined symbols
From http://lists.debian.org/debian-devel/2001/01/msg00971.html .

Countdown Clock
Countdown clock - Counts down from $MIN minutes to zero. I let the date command do the maths. This version doesn't use seq.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

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"

Count the number of characters in each line

Use jq to validate and pretty-print json output
The `jq` tool can also be used do validate json files and pretty print output: ` jq < file.json` Available on several platforms, including newer debian-based systems via `#sudo apt install jq`, mac via `brew install jq`, and from source https://stedolan.github.io/jq/download/ This alternative to the original avoids the useless use of cat

Display a list of RPMs installed on a particular date
Find out which RPMs were installed on a particular date. These would (naturally) include update RPMs. This example shows searching for "Thu 05 Mar" (with grep). Alternatively, pipe it to less so you can search inside less (with less's neat text highlighting of the search term): rpm -qa --queryformat '%{installtime} \"%{vendor}\" %{name}-%{version}-%{release} %{installtime:date}\n' | less # (this example) search term: Thu 05 Mar

Get the version of sshd on a remote system
I used this to confirm an upgrade to an SSH daemon was successful

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