What I want is printing the output the first line ( table head ) of ps aux and the grep result.After search, I come up with following.ps aux | tee >(head -1 > /dev/tty) | grep mongoBut I find the stdin of grep mongo is cut off. Also, if I omit > /dev/tty, what will the stdout of head -1 direct to? Why isn't it the console?(Yes, I know I can achive my purpose by command awk. I am just curious about why my command doesn't work?)
Why doesn't this tee with process substitution produce the 1st and chosen lines?
bash;shell;pipe;tee;process substitution