---
name: "libssh2_channel_read_ex"
section: "3"
platform: "linux"
package: "libssh2"
version: "1.11.1-7"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libssh2_channel_read_ex"
---

# libssh2\_channel\_read\_ex(3)

read data from a channel stream

## NAME

libssh2\_channel\_read\_ex - read data from a channel stream

## SYNOPSIS

```
#include <libssh2.h>
ssize_t
libssh2_channel_read_ex(LIBSSH2_CHANNEL *channel, int stream_id,
                        char *buf, size_t buflen);
ssize_t
libssh2_channel_read(LIBSSH2_CHANNEL *channel,
                     char *buf, size_t buflen);
ssize_t
libssh2_channel_read_stderr(LIBSSH2_CHANNEL *channel,
                            char *buf, size_t buflen);
```

## DESCRIPTION

Attempt to read data from an active channel stream. All channel streams have one standard I/O substream (stream\_id == 0), and may have up to 2^32 extended data streams as identified by the selected *stream\_id*. The SSH2 protocol currently defines a stream ID of 1 to be the stderr substream.

*channel* - active channel stream to read from.

*stream\_id* - substream ID number (e.g. 0 or SSH\_EXTENDED\_DATA\_STDERR)

*buf* - pointer to storage buffer to read data into

*buflen* - size of the buf storage

*[libssh2\_channel\_read(3)](/libssh2_channel_read/3.md)* and *[libssh2\_channel\_read\_stderr(3)](/libssh2_channel_read_stderr/3.md)* are macros.

## RETURN VALUE

Actual number of bytes read or negative on failure. It returns LIBSSH2\_ERROR\_EAGAIN when it would otherwise block. While LIBSSH2\_ERROR\_EAGAIN is a negative number, it is not really a failure per se.

Note that a return value of zero (0) can in fact be a legitimate value and only signals that no payload data was read. It is not an error.

## ERRORS

*LIBSSH2\_ERROR\_SOCKET\_SEND* - Unable to send data on socket.

*LIBSSH2\_ERROR\_CHANNEL\_CLOSED* - The channel has been closed.

## SEE ALSO

**[libssh2\_poll\_channel\_read(3)](/libssh2_poll_channel_read/3.md)**