systemd sd_hwdb_get 3 sd_hwdb_get sd_hwdb_seek sd_hwdb_enumerate SD_HWDB_FOREACH_PROPERTY Seek to a location in hwdb or access entries #include <systemd/sd-hwdb.h> int sd_hwdb_get sd_hwdb *hwdb const char *modalias const char *key const char **value int sd_hwdb_seek sd_hwdb *hwdb const char *modalias int sd_hwdb_enumerate sd_hwdb *hwdb const char **key const char **value SD_HWDB_FOREACH_PROPERTY hwdb modalias key value sd_hwdb_get() queries the hwdb object created earlier with sd_hwdb_new3 for entries matching the specified string modalias, and returns the value corresponding to the key key. The value is returned as a NUL-terminated string in value. It must not be modified by the caller and is valid as long as a reference to hwdb is kept. When multiple patterns in the database match modalias, the one with the highest priority is used. See hwdb7 for details. sd_hwdb_seek() selects entries matching the specified string modalias. Subsequent queries with sd_hwdb_enumerate() will access the key-value pairs for that string. sd_hwdb_enumerate() returns (in turn) all the key-value pairs defined for the string used with sd_hwdb_seek(). Each pair is returned as NUL-terminated strings in key and value. The strings must not be modified by the caller and are valid as long as a reference to hwdb is kept. When multiple patterns in the database match modalias, the combination of all matching key-value pairs is used. See hwdb7 for details. The SD_HWDB_FOREACH_PROPERTY macro combines sd_hwdb_seek() and sd_hwdb_enumerate(). No error handling is performed and iteration simply stops on error. See the example below. On success, sd_hwdb_get() and sd_hwdb_seek() return a non-negative integer. On failure, they return a negative errno-style error code. sd_hwdb_enumerate() returns a positive integer if another key-value pair was found or zero if all entries have already been enumerated. On failure, it returns a negative errno-style error code. Returned errors may indicate the following problems: -EINVAL A parameter is NULL. -ENOENT An entry for the specified modalias was not found. -EAGAIN sd_hwdb_seek() was not called before sd_hwdb_enumerate(). The effect is similar to calling systemd-hwdb query usb:v046DpC534. systemd1, systemd-udevd.service8, sd-hwdb3, systemd-hwdb8