bash

Fedora/Bash: Get the IP of enp0s3

 in Bash / GNU/Linux  tagged bash / cut / fedora / IP / sed by

Following is a small snippet that will print on screen the IP of enp0s3 (or any other device if you change the name) while in Fedora.
As you will see, it is not a very sound solution as it depends on the structure of the output of ifconfig enp0s3.

Nevertheless is works (for Fedora at least)! 🙂

ifconfig enp0s3 | grep "inet " | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' | cut -d ' ' -f 2

What this line does is: first it prints out the configuration information for enp0s3, then finds the line that contains the inet, then using sed it will trim the result (in other words, it will remove all leading and all trailing white-space from the pipe), finally cut gets the second column of the data after separating the line using the space symbol.

The Fedora version that was used for this tutorial is

$cat /etc/fedora-release 
Fedora release 23 (Twenty Three)

The version of ifconfig for this tutorial is

$ifconfig --version
net-tools 2.10-alpha

In case you want to assign the IP of enp0s3 to a variable, you can easily do as follows

IP=`ifconfig enp0s3 | grep "inet " | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' | cut -d ' ' -f 2`;

Ubuntu/Bash: Get the IP of eth0

 in Bash / GNU/Linux  tagged bash / IP / ubuntu by

Following is a small snippet that will print on screen the IP of eth0 while in Ubuntu (Both server and desktop versions).
As you will see, it is not a very sound solution as it depends on the structure of the output of ifconfig eth0.

Nevertheless is works (for Ubuntu at least)! 🙂

ifconfig eth0 | grep "inet addr" | cut -d ':' -f 2 | cut -d ' ' -f 1

What this line does is: first it prints out the configuration information for eth0, then finds the line that contains the inet addr, using cut it gets the second column of the data after separating the line using the : symbol. Right now in the pipe we will have something similar to this 192.168.1.37 Bcast, so we need to filter out the last part as well. We do the last filtering by using cut again, this time by getting the first column while using the space character as the delimiter.

The Ubuntu version that was used for this tutorial is

$lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 14.04.4 LTS
Release:	14.04
Codename:	trusty

The version of ifconfig for this tutorial is

$ifconfig --version
net-tools 1.60
ifconfig 1.42 (2001-04-13)

In case you want to assign the IP of eth0 to a variable, you can easily do as follows

ETH0=`ifconfig eth0 | grep "inet addr" | cut -d ':' -f 2 | cut -d ' ' -f 1`;

Bash: Show GIT Remote Origin for each immediate subfolder

 in Bash / GNU/Linux  tagged bash / git / GNU/Linux / howtos / Remote Origin URL by

To print on screen all the immediate subfolders and their GIT Remote Origin URL configuration we used the following command

find . -maxdepth 1 -type d \( ! -name . \) -exec bash -c "cd '{}' && echo '{}' && git config --get remote.origin.url" \;

We used the find general command to get all folders that are in depth 1, in other words all folders that are in the specific folder where we started the search.
In our case we used the dot as the starting folder which means that it will run the find in the same folder as we were navigating in.
We passed as a parameter the -type d to instruct find to show only folders and ignore the files.
The \( ! -name . \) prevents executing the command in current directory by removing it from the result set.
With the results we executed some commands on each.

Specifically, we created a new bash session for each result that navigated in the folder, printed out the name of the matched folder and then print the Remote Origin URL using the command git config --get remote.origin.url

Bash: Determine state of file

 in Bash / GNU/Linux  tagged bash / executable / exist / file / folder / not empty / readable / writable by

Following you will find some tests one can perform on a file to identify its state

Check if file $FILE does not exist

if [ ! -f "$FILE" ]; then
    echo "File $FILE does not exist";
fi

Check if file $FILE exists and is a directory

if [ -d "$FILE" ]; then
    echo "File $FILE exists and is a directory";
fi

Check if file $FILE exists and is a regular file (not a directory)

if [ -f "$FILE" ]; then
    echo "File $FILE exists and is a regular file (not a directory)";
fi

Check if file $FILE exists, we do not know what type it is (if it is a directory, socket, node, etc.)

if [ -e "$FILE" ]; then
    echo "File $FILE exists, we do not know what type it is (if it is a directory, socket, node, etc.)";
fi

Check if file $FILE exists and is a symbolic link

if [ -L "$FILE" ]; then
    echo "File $FILE exists and is a symbolic link";
fi

Check if file $FILE exists and is a socket

if [ -S "$FILE" ]; then
    echo "File $FILE exists and is a socket";
fi

Check if file $FILE exists and is not empty

if [ -s "$FILE" ]; then
    echo "File $FILE exists and is not empty";
fi

Check if file $FILE exists and is readable

if [ -r "$FILE" ]; then
    echo "File $FILE exists and is readable";
fi

Check if file $FILE exists and is writable

if [ -w "$FILE" ]; then
    echo "File $FILE exists and is writable";
fi

Check if file $FILE exists and is executable

if [ -x "$FILE" ]; then
    echo "File $FILE exists and is executable";
fi