Nice to know Stuff
Find a spezific folder by name and delete it recursivly. Search down from current directory:
# find . -type d -name "@eaDir" -print0 | xargs -0 rm -rf
michael@backup-server:/mnt/backup-disk/web$ find . -type d -name "@eaDir" ./enjoy/img/@eaDir ./enjoy/img/base/backgrounds/@eaDir ./tools/images/@eaDir ./download/languages/@eaDir ./download/templates/default/@eaDir ./download/templates/@eaDir ./download/templates/simple_image_gallery/@eaDir ./download/@eaDir ./download/index_icons/michael/@eaDir ./download/index_icons/winvista/@eaDir ./download/index_icons/kde/@eaDir ./download/index_icons/apache/@eaDir ./download/index_icons/winxp/@eaDir ./download/index_icons/osx/@eaDir ./download/files/@eaDir ./download/files/programs/@eaDir ./download/files/programs/MorphVOX Pro/@eaDir ..
Find a spezific file by name and delete it. Search down from current directory:
# find . -type f -name "Thumbs.db" -print0 | xargs -0 rm -f
michael@backup-server:/mnt/backup-disk/web$ find . -type f -name "Thumbs.db" ./enjoy/img/Thumbs.db ./enjoy/img/base/backgrounds/Thumbs.db ./tools/images/Thumbs.db ./download/index_icons/michael/Thumbs.db ./download/index_icons/winvista/Thumbs.db ./download/index_icons/kde/Thumbs.db ./download/index_icons/apache/Thumbs.db ./download/index_icons/winxp/Thumbs.db ./download/index_icons/osx/Thumbs.db ./_index_content/Thumbs.db ./books/index_icons/michael/Thumbs.db ./books/index_icons/winvista/Thumbs.db ./books/index_icons/kde/Thumbs.db ./books/index_icons/apache/Thumbs.db ..
Account Type: “Standard” or “Administrator”.
On the command line, run the command id or groups and see whether you are in the sudo group. On Ubuntu, normally, administrators are in the sudo group.
You may also have administrative access if you've been directly added to the list of sudoers — this is more likely if the administrator is familiar with Linux or Unix in general and didn't use the default Ubuntu method. Try running sudo echo ok and enter your password; if this prints ok, you're an administrator.
“grep” the available space from “df” output:
# df | grep -oP '/sda1.* \K\d+(?=\s+\d+%)'
michael@backup-server:~$ df | grep -oP '/sda1.* \K\d+(?=\s+\d+%)' 994425716 michael@backup-server:~$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 15039728 1152500 13243704 9% / devtmpfs 470184 0 470184 0% /dev tmpfs 474792 0 474792 0% /dev/shm tmpfs 474792 6308 468484 2% /run tmpfs 5120 4 5116 1% /run/lock tmpfs 474792 0 474792 0% /sys/fs/cgroup /dev/mmcblk0p1 41853 21327 20526 51% /boot tmpfs 94956 0 94956 0% /run/user/1001 /dev/sda1 1441091564 373256712 994561592 28% /mnt/backup-disk
Explanation: Here, we match /sda3, then as many characters as possible until we find a stretch of numbers (\d+) which is followed by one or more spaces (\s+), then one or more numbers (\d+) and a %. The foo(?=bar) construct is a positive lookahead, it allows you to search for the string foo only if it is followed by the string bar. The \K is a PCRE trick that means “discard anything matched up to this point”. Combined with -o, it lets you use strings that precede your pattern to anchor your match but not print them.
Without -P, things are trickier. You would need multiple passes. For example:
df | grep -o '/sda3.*%' | grep -Eo '[0-9]+ *[0-9]+%' | grep -Eo '^[0-9]+'
Split text on whitespace in terminal output
To split text on whitespace you can use grep. There’s an infinite amount of ways to do this. This is one of them.
# echo 'string --with ###ALLKINDS### 0f ::outputs' | grep -oP '[^\s]+'
# echo 'string --with ###ALLKINDS### 0f ::outputs' | grep -oP '[^\s]+' string --with ###ALLKINDS### 0f ::outputs
curl only write to file if successful status 200
Make curl get the contents of a URL and write to file, but only write to file if the response is successful:
# curl -s -S -f -o blackgate-feed.json "$blackgate_rz"
- -s keeps curl quiet by hiding progress meter and error messages
- -S shows an error message if it fails (stderr)
- -f Fail silently (no output at all) on server errors, keeping stdout clean
- -o specifies an output file
Pipe video stream from raspberry pi to local computer with ffplay
I use this to get a live video stream from my Raspberry Pi with Camera attached
Execute this on the Pi, where TARGET_IP is my local computer where I will watch the stream, and PORT is an arbitrary port number.
# raspivid -t 999999 -o - | nc -u $TARGET_IP $PORT
Execute this on the local computer where you will watch the video stream
# nc -ul $PORT | ffplay -
Generating a pseudorandom password or string in Linux bash
Define a function in e.g. ~/.bashrc
genpasswd() {
tr -dc A-Za-z0-9 < /dev/urandom | head -c ${1:-36} | xargs
}
Where 36 is default length if no parameter is given
Usage:
# genpasswd GVQ3ZHqrBRDzB1QwASA9uk6YsZPto2GWeRWR # genpasswd 7 qvPWx7N