Build a Linux Clipboard Translator with C, xclip, and translate-shell

Overview

This guide shows how to build a lightweight Linux word‑translation tool that detects a mouse left‑button release, reads the selected text from the X clipboard, translates it with translate-shell, and prints the result in the terminal.

1. Install required commands

Install xclip to access the X clipboard: $ sudo apt install xclip Common usages:

$ xclip file_name               # copy file content to X clipboard
$ xclip -selection c file_name # copy to the external clipboard
$ xclip -o                     # output X clipboard to terminal
$ xclip -selection c -o       # output external clipboard to terminal

Install translate-shell , a CLI front‑end for Google/Bing translation: $ sudo apt install translate-shell Basic commands:

$ trans en:zh [word]      # translate a single word
$ trans en:zh -b [text]  # brief translation of a short text

Internet access is required unless the default engine is changed.

2. Locate the mouse device

Mouse events are exposed under /proc/bus/input/devices. Run: $ sudo cat /proc/bus/input/devices Find the line Handlers=... eventX (e.g., event2). Verify the correct event file by monitoring its output: $ sudo cat /dev/input/event2 | hexdump If moving or clicking the mouse produces values, that eventX corresponds to your mouse.

3. Write the C program

Create a directory ~/Translator and add ct.c with the following source:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/input.h>
#include <fcntl.h>

int main(void) {
    int fd;
    struct input_event ev;
    // Adjust the device path if needed
    fd = open("/dev/input/event2", O_RDONLY);
    if (fd <= 0) {
        printf("open /dev/input/event2 error!
");
        return -1;
    }
    while (1) {
        read(fd, &ev, sizeof(ev));
        if (ev.type == EV_KEY && ev.code == BTN_LEFT && ev.value == MSC_SERIAL) {
            // Left button released – invoke translation script
            system("~/Translator/goTranslate.sh");
        }
    }
    close(fd);
    return 0;
}

Compile the program:

$ gcc ct.c -o ct

4. Create the translation shell script

Save the following as ~/Translator/goTranslate.sh and make it executable ( chmod +x):

#!/bin/bash
str_old=$(cat ~/Translator/lastContent 2>/dev/null || echo "")
str_new=$(xclip -o 2>/dev/null | xargs)
if [[ "$str_new" != "$str_old" && -n "$str_new" ]]; then
    echo -e "
"
    count=$(echo "$str_new" | wc -w)
    if [[ "$count" == "1" ]]; then
        echo -n -e "$str_new " >>~/Translator/words
        echo "$str_new" | trans :zh-CN | tail -1 | cut -c5- |
            sed "s,\x1b\[[0-9;]*[a-zA-Z],,g" | tee -a ~/Translator/words
    else
        echo "$str_new" | trans :zh-CN -b
    fi
    echo "$str_new" >~/Translator/lastContent
fi

Create an empty cache file:

$ touch ~/Translator/lastContent

5. Set up a convenient alias

Add the following line to ~/.bashrc (or the appropriate shell startup file): alias ct='sudo ~/Translator/ct' Reload the shell ( source ~/.bashrc) or open a new terminal.

6. Usage

When reading a document, select English text with the mouse. Then run the alias: $ ct The C program detects the left‑button release, the script fetches the selected text via xclip, translates it with trans, and prints the Chinese result. Keeping the terminal window small and on top prevents it from obscuring the document.

Conclusion

The solution combines standard Linux utilities ( xclip, translate-shell) with a short C program that monitors /dev/input/eventX. It provides on‑the‑fly English‑to‑Chinese translation of selected words or phrases without leaving the terminal.