systemd sd_journal_stream_fd 3 sd_journal_stream_fd sd_journal_stream_fd_with_namespace Create log stream file descriptor to the journal #include <systemd/sd-journal.h> int sd_journal_stream_fd const char *identifier int priority int level_prefix int sd_journal_stream_fd_with_namespace const char *name_space const char *identifier int priority int level_prefix sd_journal_stream_fd() may be used to create a log stream file descriptor. Log messages written to this file descriptor as simple newline-separated text strings are written to the journal. This file descriptor can be used internally by applications or be made standard output or standard error of other processes executed. sd_journal_stream_fd() takes a short program identifier string as first argument, which will be written to the journal as SYSLOG_IDENTIFIER= field for each log entry (see systemd.journal-fields7 for more information). The second argument shall be the default priority level for all messages. The priority level is one of LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, LOG_DEBUG, as defined in syslog.h, see syslog3 for details. The third argument is a boolean: if true kernel-style log level prefixes (such as SD_WARNING) are interpreted, see sd-daemon3 for more information. sd_journal_stream_fd_with_namespace() is similar to sd_journal_stream_fd(), but takes an additional name_space parameter that specifies which journal namespace to operate on. If specified as NULL the call is identical to sd_journal_stream_fd(). For details about journal namespaces, see systemd-journald.service8. It is recommended that applications log UTF-8 messages only with this API, but this is not enforced. Each invocation of these functions allocates a new log stream file descriptor, that is not shared with prior or later invocations. The file descriptor is write-only (its reading direction is shut down), and O_NONBLOCK is turned off initially. The call returns a valid write-only file descriptor on success or a negative errno-style error code. sd_journal_stream_fd() and sd_journal_stream_fd_with_namespace() are "async signal safe" in the meaning of signal-safety7. Creating a log stream suitable for fprintf3: sd_journal_stream_fd() was added in version 187. sd_journal_stream_fd_with_namespace() was added in version 256. systemd1 sd-journal3 sd-daemon3 sd_journal_print3 syslog3 fprintf3 systemd.journal-fields7