If you have Dropbox installed on several machines, sometimes one of the clients litter your Dropbox folder with conflicted copies. Their number can be up to hundred(s). How to get rid of them?
First, locate the conflicted copies:
$ cd ~/Dropbox # or wherever your Dropbox folder is $ find . | grep "conflicted copy"
Investigate the result and make sure they can be deleted.
# one more check: $ find . | grep "conflicted copy" | while read i; do echo $i; done # if you are absolutely sure, delete them: $ find . | grep "conflicted copy" | while read i; do echo $i; \rm "$i"; done
Notice that “
$i” is between quotes since these filenames contain spaces.
You have a media file (audio, video, image) and you want to get some detailed information about it: duration, bit rate, resolution, etc. How to extract these pieces of information?
Use the MediaInfo project. You can install it via your package manager and you will get a command called “mediainfo”.
$ mediainfo movie.avi
General Complete name : movie.avi Format : AVI Format/Info : Audio Video Interleave Format profile : OpenDML Format settings : rec File size : 1.27 GiB Duration : 2h 29mn Overall bit rate : 1 218 Kbps Writing application : AVI-Mux GUI 184.108.40.206, Feb 16 201019:42:50 Video ID : 0 Format : MPEG-4 Visual Format profile : Advanced Simple@L5 Format settings, BVOP : 2 Format settings, QPel : No Format settings, GMC : No warppoints Format settings, Matrix : Default (H.263) Muxing mode : Packed bitstream Codec ID : XVID Codec ID/Hint : XviD Duration : 2h 29mn Bit rate : 1 086 Kbps Width : 720 pixels Height : 304 pixels Display aspect ratio : 2.35:1 Frame rate : 23.976 fps Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Compression mode : Lossy Bits/(Pixel*Frame) : 0.207 Stream size : 1.13 GiB (89%) Writing library : XviD 64 Audio ID : 1 Format : MPEG Audio Format version : Version 1 Format profile : Layer 3 Mode : Joint stereo Mode extension : MS Stereo Codec ID : 55 Codec ID/Hint : MP3 Duration : 2h 29mn Bit rate mode : Constant Bit rate : 128 Kbps Channel(s) : 2 channels Sampling rate : 48.0 KHz Compression mode : Lossy Stream size : 136 MiB (11%) Alignment : Aligned on interleaves Interleave, duration : 747 ms (17.92 video frames) Interleave, preload duration : 216 ms Title : mp3 Writing library : LAME3.99r Encoding settings : -m j -V 4 -q 2 -lowpass 17 -b 128
pandoc input.txt -o output.pdf
By the way, pandoc can convert from / to lots of file formats.
cat file.txt | shuf
For more alternatives, see the comments at the bottom of this page.
You have a long text file and you want to process it parts by parts. For instance, you want to work with the first 50 lines, then with lines 51-100, etc.
cat file.txt | sed -n '1,50p' # or: sed -n '1,50p' file.txt
There is a command called shopt that allows you to change additional shell optional behavior.
I use both Ubuntu and Manjaro and I noticed that sometimes bash behaved differently on Manjaro. For instance, I had a folder called “Test_me”. Once accidentally I wrote “cd test_me” and Manjaro entered the folder “Test_me” (notice the capital ‘T’) without any problem. Under Ubuntu it was impossible :)
As it turned out, the different behaviour is due to different shopt settings. In the example above, “cdspell” was on in Manjaro, while in Ubuntu it was off by default.
Since I use both systems and I want bash to behave similarly, I added these lines to the end of my ~/.bashrc:
# shopt settings (normalize Ubuntu and Manjaro) shopt -s cdspell shopt -s dotglob shopt -s hostcomplete shopt -s nocaseglob shopt -u sourcepath
I switched “sourcepath” off. Read this post if you want to know why.
We know that “
source” is a bash shell built-in command that executes the content of the file passed as argument in the current shell. It has a synonym: ‘.‘ (dot).
The classical use case is “
source .bashrc” in your HOME directory. You do it when you modify your
~/.bashrc file and you want to activate the changes in the current terminal.
source is an alternative name for
. in bash) command behaves more or less the same as when executing a command.
In POSIX sh, the following two will search for a file named
foo in PATH (only).
foo . foo
while the following two will specifically run and source, respectively, the file named
foo in the current directory (only)
./foo . ./foo
Bash differs slightly (when not running in posix mode) in that when you give
source an argument without any slash (
/) characters (e.g.
source foo), it searches through the PATH variable, like POSIX sh, but then also checks the current directory, if it was not found in PATH.” (end of quote)
Because of this I ran into a strange problem. I had a file called “.venv” that I wanted to source (source .venv) but I got some error. If I renamed the file, it worked well. But I wanted to call it “.venv”. What’s wrong?
As explained above, it turned out that “source” started to look for “.venv” in the PATH first. Somehow it found a different file with the very same name and that caused the problem. When I renamed the file to “not_hidden” or “.jabba”, it worked.
The trivial way is to use “./” by telling source to take the argument from the current directory:
However, in my entire life I thought that “source .bashrc” takes the file .bashrc from the current directory. It should, in my opinion :)
If you also think that “source” shouldn’t do anything with the PATH variable, there is a cure. This feature can be switched off. The command “shopt” is a builtin that allows you to change additional shell optional behavior.
The guilty option is this one:
sourcepath If set, the source builtin uses the value of PATH to find the directory containing the file supplied as an argument. This option is enabled by default.
Simply run “shopt” to see if “sourcepath” is on for you. You can switch it off easily:
shopt -u sourcepath
To make it permanent, add this line to the end of your ~/.bashrc.
After all this ado, I could finally write this:
And this is the beauty of Linux. You learn something new every day :)