When I do
find /
on a terminal and then do on another terminal
lsof -a -d 0-2 -c fin
I see o/p listed from execution of lsof command.
But when I do
echo hi ; read -t 30 hello
hi
on the same terminal ( as find) and do (on different terminal)
lsof -a -d 0-2 -c read
I don't get any output from lsof command
Why ? Is it because read is bash built in ? Whats happening here ?
You got it right. "read" is a shell built-in. The process name remains sh (or bash, or zsh, or whatever else is your shell of choice).
Moreover, though for some shell built-ins there are binary alternatives, there isn't one for read. Really because of its syntax, it takes in the name of a shell variable that gets assigned the result of reading from the stdin. If it was an external program, it could never set the variable in the calling shell.