LinuxでBASE64

・素直にbase64

echo "test" | base64
dGVzdA==

echo "dGVzdA==" | base64 -b
test

cat test.txt | base64 > test_b64.txt

cat test_b64.txt | base64 -d > test_b64_dec.txt


・またはnkf

echo "test" | nkf -MB
dGVzdA==

echo "dGVzdA==" | nkf -mB
test

cat test.txt | nkf -MB > test_b64.txt

cat test_b64.txt | nkf -mB -d > test_b64_dec.txt