Filter multiple items from the output of a long running command

**TLDR:** How do I run handbrakecli, get progress **and** ETA, pipe into dialog without flickering. **Details:** I have a script that finds all video files in a directory and then runs handbrakecli on them one at a time. Everytime handbrakecli runs it spits out a bunch of information about the file etc. and then the line: Encoding: task 1 of 1, 3.30 % (295.53 fps, avg 303.23 fps, ETA 00h02m54s) In my script I pipe the handbrakecli command to some other commands to filter out everything except the progress and then I pipe that to dialog like so: **Snippet 1** HandBrakeCLI --preset "Normal" -i "$f" -o "$DEST" | \ stdbuf -o0 tr -s '\r' '\n' | \ stdbuf -o0 grep -oP '(?<=, )\d+(?=\.\d\d \%)' | \ dialog --gauge "$DIALOG_MSG" 10 70; This works fine. It shows the progress and it doesn't flicker. Second task was to come up with a way to show both the progress AND the ETA and this is what I came up with: **Snippet 2** HandBrakeCLI --preset "Normal" -i "$f" -o "$DEST_FULL_FILE" | \ stdbuf -oL tr -s '\r' '\n' | \ while read -r str; do local REMAINING=$(echo "$str" | grep -oP "(?<=ETA )\d\dh\d\dm\d\ds(?=\))"); local PROGRESS=$(echo "$str" | grep -oP "(?<=, )\d+(?=.\d\d)"); echo "$PROGRESS" | dialog --gauge "$DIALOG_MSG Time remaining: $REMAINING" 10 70; done This works but the dialog window flickers. I don't know if it's performance related (doubt it) or if the whole *while read* loop just doesn't work well with dialog. I also tried doing it without piping to dialog but that just showed dialog once and then didn't update it at all. **Snippet 3** HandBrakeCLI --preset "Normal" -i "$f" -o "$DEST_FULL_FILE" | \ stdbuf -oL tr -s '\r' '\n' | \ while read -r str; do local REMAINING=$(echo "$str" | grep -oP "(?<=ETA )\d\dh\d\dm\d\ds(?=\))"); local PROGRESS=$(echo "$str" | grep -oP "(?<=, )\d+(?=.\d\d)"); dialog --gauge "$DIALOG_MSG Time remaining: $REMAINING" 10 70 $PROGRESS; done Finally I tried this: **Snippet 4** HandBrakeCLI --preset "Normal" -i "$f" -o "$DEST_FULL_FILE" | \ stdbuf -o0 tr -s '\r' '\n' | ( read -r str; local REMAINING=$(echo "$str" | grep -oP "(?<=ETA )\d\dh\d\dm\d\ds(?=\))"); local PROGRESS=$(echo "$str" | grep -oP "(?<=, )\d+(?=.\d\d)"); echo "$PROGRESS"; ) | dialog --gauge "$DIALOG_MSG Time remaining: $REMAINING" 10 70; And that didn't work out well at all. I'm aware there are some fundamental things wrong here.