Shellscripts useful tips without category

shellscripts_tips.sh

# Force a shellscript to run from its folder, instead the current directory
# folder where was called from. Useful to use relative paths.

# Set the folder to project, no matter from where the script was called.                                                                                                    
SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"                                                                                                              
pushd $SCRIPT_DIR

# Test the connectivity from a machine to another and the port
nc -vv 192.168.1.200 80

# Another possible test is to start a service at destination machine, and
# check from another if the data send is received there:
# 1.- You can easely start a listener at the destination machine:
nc -vlkp 8080
# 2.- Then just send it anything and see if the listener receive it, you can
# do it with a browser pointing to http://LISTENER_IP:8080 or from console with:
nc -v LISTENER_IP 8080

# View the size of all current subfolders sorted by size
du -sh ./* | sort -hr
# du command calculate the space used, the options used are:
# s -> summarice sizes (one value per folder)
# h -> human readable
# sort command is to sort the results, the options used are:
# h -> to sort properly the values in human format
# r -> reverse results to show the bigger values first

# Generate a file of specific size (usually for testing porpouses) for example 100Mb
# Source -> https://skorks.com/2010/03/how-to-quickly-generate-a-large-file-on-the-command-line-with-linux/
dd if=/dev/urandom of=/tmp/test_100mb.txt bs=1048576 count=100