---
name: "b64decode"
section: "1"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "macos"]
url: "https://new.carta.tech/b64decode"
---

# b64decode(1)

encode / decode a binary file

## NAME

**bintrans**, **uuencode**, **uudecode**, **b64encode**, **b64decode**, **base64** – encode / decode a binary file

## SYNOPSIS

**bintrans** \[algorithm\] \[...\]

**uuencode** \[**-m**\] \[**-r**\] \[**-o** *output\_file*\] \[*file*\] *name*

**uudecode** \[**-cimprs**\] \[*file ...*\]

**uudecode** \[**-i**\] **-o** *output\_file*

**b64encode** \[**-r**\] \[**-w** *column*\] \[**-o** *output\_file*\] \[*file*\] *name*

**b64decode** \[**-cimprs**\] \[*file ...*\]

**b64decode** \[**-i**\] **-o** *output\_file* \[*file*\]

**base64** \[**-d**\] \[**-w** *column*\] \[*file*\]

## DESCRIPTION

The **uuencode** and **uudecode** utilities are used to transmit binary files over transmission mediums that do not support other than simple ASCII data. The **b64encode** utility is synonymous with **uuencode** with the **-m** flag specified. The **b64decode** utility is synonymous with **uudecode** with the **-m** flag specified.

The **base64** utility acts as a base64 decoder when passed the **--decode** (or **-d**) flag and as a base64 encoder otherwise. As a decoder it only accepts raw base64 input and as an encoder it does not produce the framing lines. **base64** reads standard input or *file* if it is provided and writes to standard output. Options **--wrap** (or **-w**) and **--ignore-garbage** (or **-i**) are accepted for compatibility with GNU base64, but the latter is unimplemented and silently ignored.

The **uuencode** utility reads *file* (or by default the standard input) and writes an encoded version to the standard output, or *output\_file* if one has been specified. The encoding uses only printing ASCII characters and includes the mode of the file and the operand *name* for use by **uudecode**.

The **uudecode** utility transforms *uuencoded* files (or by default, the standard input) into the original form. The resulting file is named either *name* or (depending on options passed to **uudecode**) *output\_file* and will have the mode of the original file except that setuid and execute bits are not retained. The **uudecode** utility ignores any leading and trailing lines.

The following options are available for **uuencode**:

- **-m**

  Use the Base64 method of encoding, rather than the traditional **uuencode** algorithm.

- **-r**

  Produce raw output by excluding the initial and final framing lines.

- **-o** *output\_file*

  Output to *output\_file* instead of standard output.

The following options are available for **uudecode**:

- **-c**

  Decode more than one uuencoded file from *file* if possible.

- **-i**

  Do not overwrite files.

- **-m**

  When used with the **-r** flag, decode Base64 input instead of traditional **uuencode** input. Without **-r** it has no effect.

- **-o** *output\_file*

  Output to *output\_file* instead of any pathname contained in the input data.

- **-p**

  Decode *file* and write output to standard output.

- **-r**

  Decode raw (or broken) input, which is missing the initial and possibly the final framing lines. The input is assumed to be in the traditional **uuencode** encoding, but if the **-m** flag is used, or if the utility is invoked as **b64decode**, then the input is assumed to be in Base64 format.

- **-s**

  Do not strip output pathname to base filename. By default **uudecode** deletes any prefix ending with the last slash '/' for security reasons.

Additionally, **b64encode** accepts the following option:

- **-w** *column*

  Wrap encoded output after *column*.

**bintrans** is a generic utility that can run any of the aforementioned encoders and decoders. It can also run algorithms that are not available through a dedicated program:

**qp** is a quoted-printable converter and accepts the following options:

- **-d**

  Decode.

- **-o** *output\_file*

  Output to *output\_file* instead of standard output.

- **-r**

  Encode/Decode in RFC2047 specific variant.

## EXAMPLES

The following example packages up a source tree, compresses it, uuencodes it and mails it to a user on another system. When **uudecode** is run on the target system, the file \`\`src\_tree.tar.Z'' will be created which may then be uncompressed and extracted into the original tree.

```
tar cf - src_tree | compress |
uuencode src_tree.tar.Z | mail user@example.com
```

The following example unpacks all uuencoded files from your mailbox into your current working directory.

```
uudecode -c < $MAIL
```

The following example extracts a compressed tar archive from your mailbox

```
uudecode -o /dev/stdout < $MAIL | zcat | tar xfv -
```

## SEE ALSO

[basename(1)](/basename/1.md), [compress(1)](/compress/1.md), [mail(1)](/mail/1.md), [uucp(1)](/uucp/1.md) (*ports/net/freebsd-uucp*), [uuencode(5)](/uuencode/5.md)

## HISTORY

The **uudecode** and **uuencode** utilities appeared in 4.0BSD.

## BUGS

Files encoded using the traditional algorithm are expanded by 35% (3 bytes become 4 plus control information).