There are times when files contain spurious Non-Printable characters. These can be due to conversion errors or the files are actually in different encoding (See "Encoding" section in the Unix vs. Dos/Windows text files chapter).
People often provide "CSV" (Comma Separated Values) files with a Non-Printable field separator. For example:
$ cat funnychars.txt | head -4
USER_IDACCT_NUMUSER_NAME
35555David
5789Carol
15555Carol
$ od -c -t x1 funnychars.txt | head -4
0000000 U S E R _ I D 001 A C C T _ N U M
55 53 45 52 5f 49 44 01 41 43 43 54 5f 4e 55 4d
0000020 001 U S E R _ N A M E \n 3 001 5 5 5
01 55 53 45 52 5f 4e 41 4d 45 0a 33 01 35 35 35
We will utilize the TR to translate the Non-Printable separator (ASCII 01) into a :
character.
$ cat funnychars.txt | head -4 | tr '\1' ':'
USER_ID:ACCT_NUM:USER_NAME
3:5555:David
5:789:Carol
1:5555:Carol