GNU/Linux

Perform diff on two folders

 in Bash  tagged diff / recursion by

To perform a recursive diff on all the files of two folders we just need to add the -r (or --recursive) parameter that recursively compares any subdirectories found.

To avoid needless messages from the tool, we can also use the -q (or --brief) parameter that reports only when files differ.

Example of performing diff on two folders recursively while preventing needless messages.


diff -rq aFolder someOtherFolder;

Compiling gr-gsm on Ubuntu 14.04 LTS

 in Applications / GNU/Linux  tagged gr-gsm / gsm / ubuntu by

Below are the steps that we followed to compile gr-gsm on Ubuntu 14.04 LTS.


sudo apt-get update;
sudo apt-get install build-essential python-dev git python-pip;
sudo pip install PyBOMBS;
sudo pybombs prefix init /usr/local -a default_prx;
sudo pybombs config default_prefix default_prx;
sudo pybombs recipes add gr-recipes git+https://github.com/gnuradio/gr-recipes.git;
sudo pybombs recipes add gr-etcetera git+https://github.com/gnuradio/gr-etcetera.git;
sudo pybombs install gr-gsm;
sudo ldconfig;

How to find lines that contain only lowercase characters

 in Bash  tagged grep / lower case / lowercase / regex / regular expression by

To print all lines that contain only lower case characters, we used the following regular expression in grep:


egrep '^[[:lower:]]+$' <file>;
#If you do not have egrep, use
grep -e '^[[:lower:]]+$' <file>;

Breakdown of the above regular expression:

  • ^ instructs the regular expression parser that the pattern should always start with the beginning of the line
  • [[:lower:]] this special instruction informs us that only lower case characters can match it
  • + the plus sign causes the preceding token to be matched one or more times
  • $ signifies the end of the line

How to create a compressed archive for each folder in current directory

 in GNU/Linux  tagged compression / current date / find / lossless / metadata / tar / xz by

The following command will create a compressed tar archive for each folder found in the current directory.
It will use the LZMA/LZMA2 compression algorithms and it supports Unix-like file system metadata as well.
It will reuse the name of the folder for the archive as well and it will append the current date to the name.


find . -maxdepth 1 -mindepth 1 -type d -exec tar cJf "{}.`date +%F`.tar.xz" '{}' \;

The parameters we used for the find command are the following:

  • -maxdepth levels Descend at most levels (a non-negative integer) levels of directories below the command line arguments. -maxdepth 0 means only apply the tests and actions to the command line arguments.
  • -mindepth levelsDo not apply any tests or actions at levels less than levels (a non-negative integer). -mindepth 1 means process all files except the command line arguments.
  • -type d Match directories (folders) only

The parameters we used for the tar command are the following: