---
name: "ms_log_l"
section: "3"
platform: "linux"
package: "libmseed-doc"
version: "2.19.8-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ms_log_l"
---

# ms\_log\_l(3)

Central logging facility for libmseed

## NAME

ms\_log - Central logging facility for libmseed

## SYNOPSIS

```
#include <libmseed.h>

int  ms_log (int level, const char *format, ...);

int  ms_log_l (MSLogParam *logp, int level, const char *format, ...);

void ms_loginit (void (*log_print)(char*), const char *logprefix,
                 void (*diag_print)(char*), const char *errprefix);

MSLogParam * ms_loginit_l (MSLogParam *logp,
               void (*log_print)(char*), const char *logprefix,
               void (*diag_print)(char*), const char *errprefix);
```

## DESCRIPTION

The **ms\_log** functions are the central logging facility for all output from libmseed functions.  They are also intended to be used by libmseed based programs if desired.

Three message levels are recognized:\
  0  : Normal log messages, printed using log\_print with logprefix\
  1  : Diagnostic messages, printed using diag\_print with logprefix\
  2+ : Error messages, printed using diag\_print with errprefix

It is the task of the **ms\_log** functions to format a message using **printf** conventions and pass the formatted string to the appropriate printing function (*log\_print* or *diag\_print*).

**ms\_log** will process messages using the global logging parameters.

**ms\_log\_l** is a reentrant version of **ms\_log**.  It will use the logging parameters specified in the supplied MSLogParam struct. If **logp** is NULL global parameters will be used, this would be equivalent to a call to ms\_log().  This is intended for use only when complicated logging schemes are desired, e.g. in a threaded application.  Note that it is not possible to set thread specific logging parameters for the internal library functions because global parameters are used.

The **ms\_loginit** functions are used to set the log and error printing functions and the log and error message prefixes used by the **ms\_log** functions.

**ms\_loginit** will operate on the global logging parameters.

**ms\_loginit\_l** is a reentrant version of **ms\_loginit**.  It will initialize or change the logging parameters specified in the MSLogParam struct.  If *logp* is NULL a new MSLogParam struct will be allocated.  A pointer to the created or re-initialized MSLogParam struct will be returned.  The returned pointer is suitable for use with **ms\_log\_l**.

Use NULL for the print function pointers or the prefixes if they should not be changed from previously set or default values.

The default values for the logging parameters are:\
   log\_print  = fprintf  (printing to standard out)\
   log\_prefix = ""\
   diag\_print = fprintf  (printing to standard error)\
   err\_prefix = "Error: "

By setting the printing functions it is possible to re-direct all of the output from these logging routines.  This is useful when the libmseed based software is embedded in a system with its own logging facilities.

Most of the libmseed internal messages are logged at either the diagnostic or error level.

## RETURN VALUES

**ms\_log** and **ms\_log\_l** return the number of characters formatted on success, and a negative value on error.

**ms\_loginit\_l** returns a pointer to the MSLogParam struct that it operated on.  If the input MSLogParam struct is NULL a new struct will be allocated with **malloc()**

## EXAMPLE

**Unless a complicated logging scheme is needed most uses of this** **logging facility will be limited to the ms\_loginit and ms\_log** **functions.**

**An example of setting the printing functions:**

```
#include <libmseed.h>
void log_print (const char *message);
void diag_print (const char *message);
main () {
  ms_loginit (&log_print, "LOG: ", &diag_print, "ERR: ");
  /* Normal log message, "LOG: " will be prefixed */
  ms_log (0, "Normal log message for %s0, argv[0]);
  /* Diagnostic message, "LOG: " will be prefixed */
  ms_log (1, "Diagnostic message for %s0, argv[0]);
  /* Error message, "ERR: " will be prefixed */
  ms_log (2, "Error message for %s0, argv[0]);
}
void log_print (const char *message) {
  /* Send message to external log message facility */
  send_log(message);
}
void diag_print (const char *message) {
  /* Send message to external error message facility */
  send_error(message);
}
```

## AUTHOR

```
Chad Trabant
IRIS Data Management Center
```