---
name: "tr"
section: "1"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/tr"
---

# tr(1)

translate characters

## NAME

**tr** – translate characters

## SYNOPSIS

**tr** \[**-Ccs**\] *string1* *string2*

**tr** \[**-Cc**\] **-d** *string1*

**tr** \[**-Cc**\] **-s** *string1*

**tr** \[**-Cc**\] **-ds** *string1* *string2*

## DESCRIPTION

The **tr** utility copies the standard input to the standard output with substitution or deletion of selected characters.

The options are as follows:

- **-C**

  Complements the set of characters in *string1*; for instance, “-C ab” includes every character except for ‘a’ and ‘b’.

- **-c**

  The same as **-C**.

- **-d**

  The **-d** option causes characters to be deleted from the input.

- **-s**

  After all deletion and translation is completed, the **-s** option squeezes multiple consecutive occurrences of the characters listed in the last operand (either *string1* or *string2*) into a single instance of the character.

In the first synopsis form, the characters in *string1* are translated into the characters in *string2* where the first character in *string1* is translated into the first character in *string2* and so on. If *string1* is longer than *string2*, the last character found in *string2* is duplicated until *string1* is exhausted.

In the second synopsis form, the characters in *string1* are deleted from the input.

In the third synopsis form, the characters in *string1* are compressed as described for the **-s** option.

In the fourth synopsis form, the characters in *string1* are deleted from the input, and the characters in *string2* are compressed as described for the **-s** option.

The following conventions can be used in *string1* and *string2* to specify sets of characters:

- character

  Any character not described by one of the following conventions represents itself.

- \\octal

  A backslash followed by 1, 2, or 3 octal digits represents a character with that encoded value. To follow an octal sequence with a digit as a character, left zero-pad the octal sequence to the full 3 octal digits.

- \\character

  A backslash followed by certain special characters maps to special values.

  - \\a

    \<alert character\>

  - \\b

    \<backspace\>

  - \\f

    \<form-feed\>

  - \\n

    \<newline\>

  - \\r

    \<carriage return\>

  - \\t

    \<tab\>

  - \\v

    \<vertical tab\>

    A backslash followed by any other character maps to that character.

- c-c

  Represents the range of characters between the range endpoints, inclusively.

- \[:class:\]

  Represents all characters belonging to the defined character class. Class names are:

  - alnum

    \<alphanumeric characters\>

  - alpha

    \<alphabetic characters\>

  - blank

    \<blank characters\>

  - cntrl

    \<control characters\>

  - digit

    \<numeric characters\>

  - graph

    \<graphic characters\>

  - lower

    \<lower-case alphabetic characters\>

  - print

    \<printable characters\>

  - punct

    \<punctuation characters\>

  - space

    \<space characters\>

  - upper

    \<upper-case characters\>

  - xdigit

    \<hexadecimal characters\>

    With the exception of the “upper” and “lower” classes, characters in the classes are in unspecified order. In the “upper” and “lower” classes, characters are entered in ascending order.

    For specific information as to which ASCII characters are included in these classes, see [isalnum(3)](/isalnum/3.md), [isalpha(3)](/isalpha/3.md), and related manual pages.

- \[=equiv=\]

  Represents all characters or collating (sorting) elements belonging to the same equivalence class as *equiv*. If there is a secondary ordering within the equivalence class, the characters are ordered in ascending sequence. Otherwise, they are ordered after their encoded values. An example of an equivalence class might be “c” and “ch” in Spanish; English has no equivalence classes.

- \[#\*n\]

  Represents *n* repeated occurrences of the character represented by *#*. This expression is only valid when it occurs in *string2*. If *n* is omitted or is zero, it is interpreted as large enough to extend the *string2* sequence to the length of *string1*. If *n* has a leading zero, it is interpreted as an octal value; otherwise, it's interpreted as a decimal value.

## EXIT STATUS

The **tr** utility exits 0 on success, and \>0 if an error occurs.

## EXAMPLES

The following examples are shown as given to the shell:

Create a list of the words in file1, one per line, where a word is taken to be a maximal string of letters.

```
$ tr -cs "[:alpha:]" "\n" < file1
```

Translate the contents of file1 to upper-case.

```
$ tr "[:lower:]" "[:upper:]" < file1
```

Strip out non-printable characters from file1.

```
$ tr -cd "[:print:]" < file1
```

## SEE ALSO

[sed(1)](/sed/1.md)

## STANDARDS

The **tr** utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification, except that the **-C** option behaves the same as the **-c** option since **tr** is not locale-aware.

System V has historically implemented character ranges using the syntax “\[c-c\]” instead of the “c-c” used by historic BSD implementations and standardized by POSIX. System V shell scripts should work under this implementation as long as the range is intended to map in another range, i.e., the command “tr \[a-z\] \[A-Z\]” will work as it will map the ‘\[’ character in *string1* to the ‘\[’ character in *string2*. However, if the shell script is deleting or squeezing characters as in the command “tr -d \[a-z\]”, the characters ‘\[’ and ‘\]’ will be included in the deletion or compression list, which would not have happened under an historic System V implementation. Additionally, any scripts that depended on the sequence “a-z” to represent the three characters ‘a’, ‘-’, and ‘z’ will have to be rewritten as “a\\-z”.

The **tr** utility has historically not permitted the manipulation of NUL bytes in its input and, additionally, has stripped NUL's from its input stream. This implementation has removed this behavior as a bug.

The **tr** utility has historically been extremely forgiving of syntax errors: for example, the **-c** and **-s** options were ignored unless two strings were specified. This implementation will not permit illegal syntax.

It should be noted that the feature wherein the last character of *string2* is duplicated if *string2* has less characters than *string1* is permitted by POSIX but is not required. Shell scripts attempting to be portable to other POSIX systems should use the “\[#\*\]” convention instead of relying on this behavior.