cat 1.txt | parallel
seq 0 20 | parallel echo {}
seq 0 20 | parallel "sleep 1; echo {}"

# -j control number of jobs
seq 0 20 | parallel -j 10  "sleep 1; echo {}"
seq 0 20 | parallel -j 50% "sleep 1; echo {}"

# -k keep original sequence for output
cat 2.txt | parallel
cat 2.txt | parallel -k




./code.py 1
seq 1 8 |parallel ./code.py {}
time seq 1 8 |parallel -j1 ./code.py {}
time seq 1 8 |parallel     ./code.py {}
time seq 1 8 |parallel -j8 ./code.py {}
/bin/ls -1 *png | parallel "convert {} {.}.jpg ; rm -f {}"

