Ubuntu – How to check in a bash script if passed argument is file or directory

bashscripts

I have to write a simple bash script in Ubuntu which would allow me to pass it some arguments and I want to check if these arguments which can contain spaces are files or directories. How can I do this?

Best Answer

Example script:

#!/bin/bash
# This is a simple demo script
# It takes 3 parameters and checks if they are files or directories

echo "Welcome to my script"

if [[ -f "$1" || -d "$1" ]]
then
    echo "The First argument is a file or directory"
fi

if [[ -f "$2" || -d "$2" ]]
then
    echo "The second argument is a file or directory"
fi

if [[ -f "$3" || -d "$3" ]]
then
    echo "The third argument is a file or directory"
fi

echo "Bye!"

Example scenario

I saved script as ~/script.sh and did chmod +x script.sh

karimov-danil@Karimov-Danil:~$ ./script.sh "Шаб лоны" "Обще доступные" "ta lk" 
Welcome to my script
The First argument is a file or directory
The second argument is a file or directory
The third argument is a file or directory
Bye!

Note: you should pass arguments inside double-quotes.

Related Solutions

Ubuntu – Copy file to same directory with appended filename Via SSH Bash Script

You can do

cp /path/files/file /path/files/file-$(date +%Y%m%d)

To do the same for multiple files e direcories:

timestamp=$(date +%Y%m%d)
for f in /path/files/*; do
    cp -a "$f" "$f-$timestamp"
done

Ubuntu – How to check for apt-get errors in a bash script

The simplest approach is to have your script continue only if apt-get exits correctly. For example:

sudo apt-get install BadPackageName && 
## Rest of the script goes here, it will only run
## if the previous command was succesful

Alternatively, exit if any steps failed:

sudo apt-get install BadPackageName || echo "Installation failed" && exit

This would give the following output:

terdon@oregano ~ $ foo.sh
[sudo] password for terdon: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package BadPackageName
Installation failed

This is taking advantage of a basic feature of bash and most (if not all) shells:

&& : continue only if the previous command succeeded (had an exit status of 0)
||: continue only if the previous command failed (had an exit status of not 0)

It is the equivalent of writing something like this:

#!/usr/bin/env bash

sudo apt-get install at

## The exit status of the last command run is 
## saved automatically in the special variable $?.
## Therefore, testing if its value is 0, is testing
## whether the last command ran correctly.
if [[ $? > 0 ]]
then
    echo "The command failed, exiting."
    exit
else
    echo "The command ran succesfuly, continuing with script."
fi

Note that if a package is already installed, apt-get will run successfully, and the exit status will be 0.