In Linux environments, pts (pseudo-terminal slave) refers to virtual terminal devices created for user sessions. When you run the who command, you'll see output like this:

user1     pts/0        2023-04-15 14:30 (192.168.1.10)
user2     pts/1        2023-04-15 14:32 (192.168.1.15)

The simplest way to send a message is using the write command:

write username pts/number

For the example in question:

write yang pts/6

After executing this command, type your message and press Ctrl+D to send. The recipient will see:

Message from yang@hostname on pts/3 at 10:30 ...
Hello there!
EOF

For more control, you can pipe messages directly:

echo "Server maintenance in 5 minutes" | write yang pts/6

Or send from a file:

write yang pts/6 < message.txt

To send to all users (requires root):

echo "EMERGENCY: System rebooting NOW" | wall

If messages aren't delivered:

• Check if the user has messaging disabled with mesg n (enable with mesg y)
• Verify the pts session still exists with who
• Try the full format: write yang@10.231.22.12

For interactive chatting:

talk yang@10.231.22.12

In Unix/Linux systems, pts (pseudo-terminal slave) devices represent virtual terminals created for user sessions. When you run the who command, it displays active terminal sessions like this:

user1     pts/0        2023-01-15 14:30 (192.168.1.10)
user2     pts/1        2023-01-15 14:35 (192.168.1.20)

There are several ways to send messages to terminal sessions:

# Method 1: Using write command
write username pts/1

# Method 2: Using wall (broadcast to all)
echo "Message" | wall

# Method 3: Using mesg utility
mesg y  # Enable receiving messages

To target a specific pts device directly:

# Method 1: Using echo to the device file
echo "Hello from terminal" > /dev/pts/1

# Method 2: Using write with terminal specification
write user1 pts/1

Here's a complete example of sending a message programmatically:

#!/bin/bash
# Get target pts from who output
TARGET_PTS=$(who | grep username | awk '{print $2}')

# Send message
echo "Important system notification" > /dev/$TARGET_PTS

# Alternative with formatted message
printf "\033[1;31mURGENT:\033[0m System maintenance in 5 minutes\n" > /dev/$TARGET_PTS

Remember that:

• User must have mesg y set to receive messages
• You need appropriate permissions to write to the pts device
• Sudo might be required for system-wide messaging

If messages aren't being received:

# Check if user has messages enabled
who -T | grep username

# Verify terminal device exists
ls -l /dev/pts/