Bash Script to Test Internet Connectivity Quickly

Use a Bash script with ping -c 1 google.com >/dev/null 2>&1 and check $? to test internet connectivity.

Examples

Inputping -c 1 google.com

Output1 packets transmitted, 1 received, 0% packet loss, time 0ms

Inputping -c 1 invalid.domain

Outputping: unknown host invalid.domain

Inputping -c 1 8.8.8.8

Output1 packets transmitted, 1 received, 0% packet loss, time 0ms

How to Think About It

To test internet connectivity, the script tries to send one network packet to a reliable website like google.com using ping. If the ping succeeds, it means the internet is reachable; if it fails, the internet is not connected.

Algorithm

1

Send one ping packet to a known website.

2

Check the exit status of the ping command.

3

If the exit status is zero, print 'Internet is connected'.

4

Otherwise, print 'Internet is not connected'.

Code

bash

#!/bin/bash

ping -c 1 google.com >/dev/null 2>&1
if [ $? -eq 0 ]; then
  echo "Internet is connected"
else
  echo "Internet is not connected"
fi

Output

Internet is connected

Dry Run

Let's trace the script when internet is connected.

1

Run ping command

ping -c 1 google.com runs and returns exit status 0

2

Check exit status

$? equals 0, meaning success

3

Print result

Print 'Internet is connected'

Step	Command	Exit Status	Output
1	ping -c 1 google.com	0	No output (redirected)
2	Check $? == 0	true	N/A
3	echo result	N/A	Internet is connected

Why This Works

Step 1: Ping command tests connectivity

The ping command sends a small packet to google.com to check if it is reachable.

Step 2: Exit status shows success or failure

The shell variable $? holds the exit status of the last command; 0 means success.

Step 3: Conditional prints result

The script uses if to print a message based on whether the ping succeeded.

Alternative Approaches

Using curl to check connectivity

bash

#!/bin/bash
curl -s --head http://google.com | head -n 1 | grep "HTTP/" >/dev/null
if [ $? -eq 0 ]; then
  echo "Internet is connected"
else
  echo "Internet is not connected"
fi

Uses HTTP request instead of ping; useful if ping is blocked but HTTP works.

Using timeout with ping

bash

#!/bin/bash
if ping -c 1 -W 2 google.com >/dev/null 2>&1; then
  echo "Internet is connected"
else
  echo "Internet is not connected"
fi

Adds a 2-second timeout to avoid long waits if network is down.

Complexity: O(1) time, O(1) space

Time Complexity

The script runs a single ping command which takes constant time regardless of network size.

Space Complexity

The script uses minimal memory, only storing the exit status and printing a message.

Which Approach is Fastest?

Using ping with one packet is fastest; curl adds HTTP overhead but can work when ping is blocked.

Approach	Time	Space	Best For
Ping single packet	O(1)	O(1)	Quick basic connectivity check
Curl HTTP head	O(1)	O(1)	When ping is blocked but HTTP works
Ping with timeout	O(1)	O(1)	Faster failure detection on no network