---
name: "explain_linkat"
section: "3"
platform: "linux"
package: "libexplain-dev"
version: "1.4.D001-16"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/explain_linkat"
---

# explain\_linkat(3)

explain linkat(2) errors

## NAME

explain\_linkat - explain [*linkat*(2)](/linkat/2.md) errors

## SYNOPSIS

\#include \<libexplain/linkat.h\>

const char \*explain\_linkat(int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);\
 const char \*explain\_errno\_linkat(int errnum, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);\
 void explain\_message\_linkat(char \*message, int message\_size, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);\
 void explain\_message\_errno\_linkat(char \*message, int message\_size, int errnum, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);

## DESCRIPTION

These functions may be used to obtain explanations for errors returned by the [*linkat*(2)](/linkat/2.md) system call.

### explain\_linkat

const char \*explain\_linkat(int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);

The **explain\_linkat** function is used to obtain an explanation of an error returned by the [*linkat*(2)](/linkat/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

The *errno* global variable will be used to obtain the error value to be decoded.

- *old\_fildes*

  The original old\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *old\_path*

  The original old\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_fildes*

  The original new\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_path*

  The original new\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- Returns:

  The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

**Note:** This function is **not** thread safe, because it shares a return buffer across all threads, and many other functions in this library.

**Example:** This function is intended to be used in a fashion similar to the following example:

`if (linkat(old_fildes, old_path, new_fildes, new_path, flags) < 0)`

```
{
```

`fprintf(stderr, "%s\n", explain_linkat(old_fildes, old_path, new_fildes,` `new_path, flags));`

```
    exit(EXIT_FAILURE);
}
```

The above code example is available pre-packaged as the [*explain\_linkat\_or\_die*(3)](/explain_linkat_or_die/3.md) function.

### explain\_errno\_linkat

const char \*explain\_errno\_linkat(int errnum, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);

The **explain\_errno\_linkat** function is used to obtain an explanation of an error returned by the [*linkat*(2)](/linkat/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

- *errnum*

  The error value to be decoded, usually obtained from the *errno* global variable just before this function is called. This is necessary if you need to call **any** code between the system call to be explained and this function, because many libc functions will alter the value of *errno*.

- *old\_fildes*

  The original old\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *old\_path*

  The original old\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_fildes*

  The original new\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_path*

  The original new\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- Returns:

  The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

**Note:** This function is **not** thread safe, because it shares a return buffer across all threads, and many other functions in this library.

**Example:** This function is intended to be used in a fashion similar to the following example:

`if (linkat(old_fildes, old_path, new_fildes, new_path, flags) < 0)`

```
{
    int err = errno;
```

`fprintf(stderr, "%s\n", explain_errno_linkat(err, old_fildes, old_path,` `new_fildes, new_path, flags));`

```
    exit(EXIT_FAILURE);
}
```

The above code example is available pre-packaged as the [*explain\_linkat\_or\_die*(3)](/explain_linkat_or_die/3.md) function.

### explain\_message\_linkat

void explain\_message\_linkat(char \*message, int message\_size, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);

The **explain\_message\_linkat** function is used to obtain an explanation of an error returned by the [*linkat*(2)](/linkat/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

The *errno* global variable will be used to obtain the error value to be decoded.

- *message*

  The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

- *message\_size*

  The size in bytes of the location in which to store the returned message.

- *old\_fildes*

  The original old\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *old\_path*

  The original old\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_fildes*

  The original new\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_path*

  The original new\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

**Example:** This function is intended to be used in a fashion similar to the following example:

`if (linkat(old_fildes, old_path, new_fildes, new_path, flags) < 0)`

```
{
    char message[3000];
```

`explain_message_linkat(message, sizeof(message), old_fildes, old_path,` `new_fildes, new_path, flags);`

```
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}
```

The above code example is available pre-packaged as the [*explain\_linkat\_or\_die*(3)](/explain_linkat_or_die/3.md) function.

### explain\_message\_errno\_linkat

void explain\_message\_errno\_linkat(char \*message, int message\_size, int errnum, int old\_fildes, const char \*old\_path, int new\_fildes, const char \*new\_path, int flags);

The **explain\_message\_errno\_linkat** function is used to obtain an explanation of an error returned by the [*linkat*(2)](/linkat/2.md) system call. The least the message will contain is the value of `strerror(errno)`, but usually it will do much better, and indicate the underlying cause in more detail.

- *message*

  The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

- *message\_size*

  The size in bytes of the location in which to store the returned message.

- *errnum*

  The error value to be decoded, usually obtained from the *errno* global variable just before this function is called. This is necessary if you need to call **any** code between the system call to be explained and this function, because many libc functions will alter the value of *errno*.

- *old\_fildes*

  The original old\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *old\_path*

  The original old\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_fildes*

  The original new\_fildes, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *new\_path*

  The original new\_path, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

- *flags*

  The original flags, exactly as passed to the [*linkat*(2)](/linkat/2.md) system call.

**Example:** This function is intended to be used in a fashion similar to the following example:

`if (linkat(old_fildes, old_path, new_fildes, new_path, flags) < 0)`

```
{
    int err = errno;
    char message[3000];
```

`explain_message_errno_linkat(message, sizeof(message), err, old_fildes,` `old_path, new_fildes, new_path, flags);`

```
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}
```

The above code example is available pre-packaged as the [*explain\_linkat\_or\_die*(3)](/explain_linkat_or_die/3.md) function.

## SEE ALSO

- [*linkat*(2)](/linkat/2.md)

  create a file link relative to directory file descriptors

- [*explain\_linkat\_or\_die*(3)](/explain_linkat_or_die/3.md)

  create a file link relative to directory file descriptors and report errors

## COPYRIGHT

libexplain version 1.4\
 Copyright (C) 2013 Peter Miller