sed is a very handy Linux tool to search for and/or modify text. You can use it to modify the contents of files without having to manually go into them via vi.
Thanks to Stack Overflow I learned the syntax:
sed -i <filename> -e 's/<string to look for>/<string to replace it>/g'
Handy.
I recently had a need to mount a folder over SSH to allow my file manager to browse through the files on a remote system. Two great resources led me to the solution to this problem: sshfs
I first came across this little tutorial on how to install sshfs on my shiny new Linux Mint 18 box:
sudo apt-get install sshfs
sudo mkdir /mnt/droplet #<--replace "droplet" with whatever you prefersudo sshfs -o allow_other,defer_permissions root@xxx.xxx.xxx.xxx:/ /mnt/dropletPretty slick. If you want to use a keyfile instead of being prompted for a password, you can use the IdentityFile option:
sudo sshfs -o allow_other,defer_permissions,IdentityFile=~/.ssh/id_rsa root@xxx.xxx.xxx.xxx:/ /mnt/dropletYou can have this handled in /etc/fstab for automounting. Thanks to this Arch Linux guide for the info. (The command below requires systemd.)
user@host:/remote/folder /mount/point fuse.sshfs noauto,x-systemd.automount,_netdev,users,idmap=user,IdentityFile=/home/user/.ssh/id_rsa,allow_other,reconnect 0 0
I tweaked my /etc/fstab file a bit because it complained that allow_other required a configuration change. Since I’m the only user of this box it didn’t matter to me. Here is my configuration:
nicholas@remote:/ /home/desktop/remote fuse.sshfs noauto,x-systemd.automount,_netdev,users,idmap=user,IdentityFile=/home/desktop/.ssh/keyfile,reconnect,allow_other 0 0
I’m mounting the root folder of my remote machine into a folder named remote on my desktop machine. I generated ssh keyfiles so that no password was required. Now the mount shows up under “Devices” in my file manager and a simple click mounts the folder gets me there. Sweet.
Edit 2/25/18: Added allow_other option per this article
IrfanView is a very versatile little program that you can use to manipulate and view image files. I am very familiar with it and often find myself wishing I could use it in Linux. Well, it turns out I can!
There are a few things you need to do. First, install wine
#For debian-based distros sudo apt-get install wine
After wine is installed, use it to install irfanview
wine iview442_setup.exe
If you get the following error, it means you don’t have mfc42.dll installed:
err:module:import_dll Library MFC42.DLL (which is needed by L"Z:\\home\\nicholas\\Downloads\\iview442_setup.exe") not foun
The solution is to use winetricks to install mcf42.dll (thanks to winehq for the soultion to this)
winetricks -q mfc42
Optionally you can make wine your default image program (or just have it in the list of available image handling programs.) The way to do this is to write a quick script and mark it executable (thanks to linuxquestions for the answer on how to do this)
#!/bin/sh
IRFANVIEW="C:\\Program Files\Irfanview (x86)\i_view32.exe"
ROOT_DRIVE="Z:\\"
for arg
do
wine "$IRFANVIEW" "${ROOT_DRIVE}$(echo "$arg" | sed 's/\//\\/g')"
done
You may need to tweak it a little bit if you don’t have 64bit wine installed. Save that file somewhere you will remember and then mark it executable with chmod +x.
Lastly, when you right click a file and do open with, simply point it to the above script. The result: wine goodness.
My parents got a shiny new Netgear R80000 wireless router which supports OpenVPN out of the box. The client configuration it generates doesn’t work right away, though, when I try to connect from my Linux Mint desktop. The connection is successful but I can’t ping or reach anything on the other network.
I discovered on this forum that you must add a couple options to the config file the router produces. You can do this either on the command line or by modifying the config file. The options are to add an interface to the VPN and to create a route to the network, like so:
--ifconfig 192.168.1.5 255.255.255.0 --route 192.168.1.1
I took the generated non-windows VPN configuration from their router, unzipped it on my linux desktop, and then ran this command:
sudo openvpn --config parents.ovpn --ifconfig 192.168.1.5 255.255.255.0 --route 192.168.1.1
It worked like a charm.
I recently needed a quick and dirty way to crop the bottom chunk of a large batch of scanned photos. Thanks to Linux and FOSS, this is possible with a fantastic tool known as imagemagick.
Simply install imagemagick to get the necessary tools
#Assuming you have a redhat based distro sudo yum install ImageMagick*
Once installed use the mogrify tool (part of ImageMagick) to quickly chop the bottom part off:
mogrify -chop 0x45+0+0 -gravity South *.jpg
The above example chops the bottom 45 pixels off of every picture in the directory you’re in. Thanks to this site for the info. Handy.
I came across a need to install multiple patches manually (via SSH) on one of my xenservers. It’s quite tedious to do this manually so I found a way to here.)
Download all the patch .zip files to a directory your xenserver can access. Then, extract them all with this command:
find *.zip -exec unzip {} \;
Next, upload all the .xsupdates:
find *.xsupdate -exec xe patch-upload file-name={} \;
This spits out a bunch of UUIDs. Make note of these. You will also need to get your host-uuid by using the
xe host-list
command.
Lastly, a quick for loop applies the patches we want (replace the UUIDs with those of the patches uploaded earlier and the host-uuid with yours)
for file in c3520494-be00-4133-afb3-adf8ab5edb11 7fea2d85-7ce1-428c-a92f-57e37551d6f1 d9862b7f-9be6-4672-b9a8-4f52f776fd03 a424dfe5-8be8-4bd6-a49e-62620e369a43 e28bb0ae-e43f-46d9-9147-c7dc712508eb; do xe patch-apply uuid=$file host-uuid=46f8ef28-8ee1-44b5-967c-b8e48585094b; done
That did the trick for me. After applying the patches I came across this post which appears to have a much better script. Whatever works.
Update: Google released a ChromeOS update that broke the openvpn script. Find the updated version here.
Update 3/29/17: Added a DNS suffix line to fix broken DNS
I posted a little while ago about how to get openvpn working on your chromebook. That guide required that you run openvpn outside your chroot on the chromebook instance itself.
Lately I’ve been really feeling the need to have openvpn run within a crouton chroot instead. The solution is to take the script from the post above and divide it into two parts. One part you will still have to run outside your chroot but you will only have to do it once on each reboot. The other part can safely live inside your chroot.
First, on your chromebook itself (not in a chroot) make a small script to tell the shill service not to kill tun0:
sudo echo " #!/bin/bash #Allows the tun0 device to function sudo stop shill sudo start shill BLACKLISTED_DEVICES=tun0" > /usr/local/bin/shill chmod +x /usr/local/bin/shill
Next, create this script within your chroot. Be sure to modify the environment variables to suit your setup.
#!/bin/bash CONF_DIR="/path/to/directory/openvpn/config/is/in" CONF_FILE="FILENAME_OF_OVPN_FILE" NAMESERVER="IP_OF_DNS_SERVER_YOU_WANT_TO_USE" SEARCH="DNS_SUFFIX_YOU_WANT_TO_USE" cd "$CONF_DIR" # Add google DNS on top of current ones, since openvpn command does not do it sudo sed -i "1s/^/# new DNS\nsearch $SEARCH\nnameserver $NAMESERVER\n# old DNS\n/" /etc/resolv.conf sudo openvpn --config "$CONF_FILE" --dev tun0 # When ctrl-c is hit remove tun0 and cleanup the DNS sudo openvpn --rmtun --dev tun0 sudo sed -i '/# new DNS/,/# old DNS/d' /etc/resolv.conf trap 2
Voila, we now have openvpn working inside our chroots again.
This is a short note of what to do when you change size of the physical disk an LVM setup, such as the default configuration in CentOS 7.
pvresize <path to enlarged partition>
lvextend <lv path> -l100%FREE
resize2fs <lv path>
#If you're running CentOS 7, the default filesystem is actually XFS, not ext4. In that case:
xfs_growfs <lv path>
I love Linux Mint but a frustration of mine is the fact that the mouse cursors are inconsistent. If you change the mouse theme in the themes settings it will change for most windows, but certain windows such as chrome or wine revert to the system default mouse cursor.
I’ve finally found a fix courtesy of Ubuntu Forums. The problem lies with the x-cursor-theme being independent of the theme set in cinnamon. What you have to do is run a command to update the x-cursor-theme.
First, find the name of the mouse cursor you want from a list of your installed themes:
ls /usr/share/icons
Set an environment variable of the theme you want. Specify the folder name of the theme. For example, for DMZ-Black cursor:
CURSOR=DMZ-Black
Lastly run the command to update your cursor:
gsettings set org.gnome.desktop.interface cursor-theme "$CURSOR" && sudo update-alternatives --set x-cursor-theme /usr/share/icons/$CURSOR/cursor.theme
That’s it! You now have consistent mouse cursors. OCD demons satisfied.
Recently I had to compile ffmpeg from scratch on CentOS 7. The reason? I wanted libfdk_aac support. Here are my notes on the procedure. The how-to on https://trac.ffmpeg.org/wiki/CompilationGuide/Centos was actually quite helpful and accurate.
Install necessary dependencies and set up build folder
yum install autoconf automake cmake freetype-devel gcc gcc-c++ git libtool make mercurial nasm pkgconfig zlib-devel mkdir ~/ffmpeg_sources
Build necessary components
I only needed x264 and libfdk_aac, so that’s all I ended up doing:
#yasm cd ~/ffmpeg_sources git clone --depth 1 git://github.com/yasm/yasm.git cd yasm autoreconf -fiv ./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin" make make install make distclean
#libx264 cd ~/ffmpeg_sources git clone --depth 1 git://git.videolan.org/x264 cd x264 PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure --prefix="$HOME/ffmpeg_build" --bindir="$HOME/bin" --enable-static make make install make distclean
#libfdk_aac cd ~/ffmpeg_sources git clone --depth 1 git://git.code.sf.net/p/opencore-amr/fdk-aac cd fdk-aac autoreconf -fiv ./configure --prefix="$HOME/ffmpeg_build" --disable-shared make make install make distclean
Compile ffmpeg
I actually specified a git mirror because the sources at ffmpeg site were glacially slow.
cd ~/ffmpeg_sources git clone https://github.com/FFmpeg/FFmpeg.git cd FFmpeg PKG_CONFIG_PATH="$HOME/FFmpeg_build/lib/pkgconfig" ./configure --prefix="$HOME/FFmpeg_build" --extra-cflags="-I$HOME/FFmpeg_build/include" --extra-ldflags="-L$HOME/FFmpeg_build/lib" --bindir="$HOME/bin" --pkg-config-flags="--static" --enable-gpl --enable-nonfree --enable-libfdk-aac --enable-libx264 make make install make distclean hash -r
Optionally, remove existing ffmpeg
sudo yum remove ffmpeg
That was it! After a bit of compile time ffmpeg worked with the items I wanted it to.