tee — split stdout to terminal and file simultaneously

linux-tee.sh

# tee — write to stdout AND a file at the same time

<command> | tee output.log          # overwrite
<command> | tee -a output.log       # append
<command> | tee file1 file2         # fan out to multiple files

# The AI workflow pattern — log + timestamps + live view in one pipeline:
agent-command 2>&1 | ts '[%H:%M:%S]' | tee run-$(date +%Y%m%d-%H%M%S).log

# Process and preserve the original simultaneously:
cat data.jsonl \
  | tee data-raw-copy.jsonl \
  | python3 transform.py \
  | tee data-transformed.jsonl \
  | wc -l