Comment 2 for bug 1854113

I just copy possible implementation of pbcopy and pbpaste for Linux from #1854092. That issue has more examples of similar commands for PowerShell, etc

```
#!/bin/sh
# print data from clipboard to stdout, again and again...

MODE="xclip"
#MODE="xsel" # doesn't work well, clipboard is not cleaned and the same text is printed again and again :-(

pbcopy ()
{
   if [ "$MODE" = "xclip" ]; then
     xclip -selection clip -i
   else
     xsel --clipboard --input
   fi
}

pbpaste ()
{
   if [ "$MODE" = "xclip" ]; then
     xclip -selection clip -o
   else
     xsel --clipboard --output
   fi
}

# MAIN
pbcopy </dev/null # clear clipboard
while :; do
   TXT="$(pbpaste)"
   if [ -n "$TXT" ]; then
      echo "$TXT"
      pbcopy </dev/null # clear clipboard
   else
      sleep 0.1 # sleep 100ms
   fi
done
```