A better find
I keep using the find command in Unix as such: “find / -name SOMETHING” (Yes, I know there’s locate, too). You always get an error message when you hit a directory you don’t have permissions for, but I usually don’t care about those directories anyway, so it makes sense to pipe those error messages that appear on stderr to /dev/null. This works like this:
find / -name SOMETHING 2> /dev/null
Display progress when using DD
dd if=INFILE of=OUTFILE bs=4M status=progress
Rescuing delete files in Linux
It happens. You delete a file, but not to the recycle bin, and need it back – BAD. This happened to me for a source file. Here’s what to do (based on this).
Drop to the Linux command line. If you’re on a graphical user interface press CTRL+ALT+F3 and you should be on terminal tty3. Log in like you usually would. Keep in mind you’ll need root privileges later on…
Tell all users you’re going to single user mode:
wall
Wait a bit and press CTRL+D to put in a command. Go to single user mode to prevent stuff being written to disk:
init 1
Use grep to recover your file:
grep -i -a -B20 -A100 'some text from the file' /dev/sda1 > dump.txt
The grep commands are:
-i : Ignore case distinctions in both the PATTERN and the input files i.e. match both uppercase and lowercase character.
-a : Process a binary file as if it were text
-B Print number lines/size of leading context before matching lines.
-A: Print number lines/size of trailing context after matching lines.
If you now have a file too big to edit, try copying only a few lines to another file:
head -100 dump.txt > 100lines.txt
Find the device name of your WiFi adapter
iwconfig | grep --color=never "IEEE 802" | sed "s/^\W(\w+)\b./\1/"
Recursively find files with extension and pipe to program
This command searches (all *.h/.hpp/.hxx/.c/.cpp/.cxx files) recursively in the current directory and pipes all files to clang-format as a file list in one command. It also excludes the “build” directory (I use CMake), but you can just omit the “grep” step to remove that.
shopt -s globstar extglob failglob && ls **/*.@(h|hpp|hxx|c|cpp|cxx) | grep -v build | tr '\n' ' ' | xargs clang-format -iCopy files from an m3u playlist to an extra directory addding the file number
I use this to create mixtape playlist as an m3u file and then copy all files to an extra directory in the right order. Replace “test.m3u” by you playlist, /test with the output folder and “cp” by “mv” to move the files.
grep -v '#' test.m3u | tr -d '\r' | awk '{ print "cp \"" $0 "\" \"test/" NR " - " $0 "\""}' | sh
Print the return code of a shell command
echo $?
You can find some other Linux stuff here.
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