trim
-c, --complement
-d, --delete
-s, --squeeze-repeats
-t, --truncate-set1# 공백 하나도 없이 나옴
$ cat access.log | tr -d " "
# 반복되는 T 압축 : TTT -> T 로 변환 (--squeeze-repeats)
$ cat access.log | tr -s "T"
echo "AABBCC" | tr A 1
11BBCC
echo "AaBbCc" | tr '[A-Z]' '[a-z]'
aabbcc
echo -e "a\\tb" | tr '\\t' ','
a,b
echo "AaBbCc" | tr -d '[A-Z]'
abc
echo "AAA_BBB_CCC" | tr -s '[A-Z]'
A_B_C
echo "CC_BB_AA" | tr -t 'ABC' '123'
33_22_11