[sh] `cmd > stderr.txt 2>&1` or `cmd >> stderr.txt 2>&1`

cmd > stdin.txt 0>&1
cmd >> stdin.txt 0>&1

cmd > stdout.txt
cmd >> stdout.txt
cmd > stdout.txt 1>&1
cmd >> stdout.txt 1>&1

cmd > stderr.txt 2>&1
cmd >> stderr.txt 2>&1

https://june98.tistory.com/102

Crontab 로그(log) 남기는 방법 (feat. 출력 리다이렉션, 2>&1의 의미)