perl -ne 'print if /^1234/'

sed -ne '/^1234/p'

awk '/^1234/'

grep '^1234'

ruby -ne 'print if /^1234/'

python -c 'import fileinput;print "n".join([l for l in fileinput.input() if l.startswith("1234")])'

perl -ne'print if /^1234/' file

grep ^1234 file

findstr /r ^1234 file

sed -ne '/^1234/p' somefile
awk '/^1234/{print}' somefile
grep '^1234' somefile