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9.1 tr: Translate, squeeze, and/or delete characters


tr [option]… set1 [set2]

tr copies standard input to standard output, performing one of the following operations:

The set1 and (if given) set2 arguments define ordered sets of characters, referred to below as set1 and set2. These sets are the characters of the input that tr operates on.

The program accepts the following options. Also see Common options. Options must precede operands.


This option replaces set1 with its complement (all of the characters that are not in set1). Currently tr fully supports only single-byte characters. Eventually it will support multibyte characters; when it does, the -C option will cause it to complement the set of characters, whereas -c will cause it to complement the set of values. This distinction will matter only when some values are not characters, and this is possible only in locales using multibyte encodings when the input contains encoding errors.


Delete characters in set1, do not translate


Replace each sequence of a repeated character that is listed in the last specified set, with a single occurrence of that character.


First truncate set1 to length of set2.

An exit status of zero indicates success, and a nonzero value indicates failure.

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