Provides a way to examine memory in the current process address space. Use of this function requires information about GT.M internals, which may change from release to release. Contact FIS support for information on techniques for using $ZPEEK() in largely release independent ways.

The $ZPEEK() function returns the contents of the memory requested as a string depending on the requested (or defaulted) formatting.

The format of the $ZPEEK() function is:

$ZPEEK("mnemonic[:argument]",offset,length[,format])
[Note]Notes
  • $ZPEEK() has no UTF-8 checking. It is possible for values returned by the 'C' and 'S' codes to have invalid UTF-8 values in them. Take care when processing values obtained by these codes to either use "VIEW NOBADCHAR" when dealing with such values and/or use the $Zxxx() flavors of functions like $ZPIECE(), $ZEXTRACT(),etc which also do not raise BADCHAR errors when encountering invalid UTF-8 encoded strings.

  • Note that $ZPEEK() with 8 byte numeric formatting can return numeric string values that exceed GT.M's current limit of 18 digits of precision. If the values are used as strings, the extra digits are preserved, but if used arithmetically, the lower precision digits can be lost.

  • When values from replication structures are requested and the structures are not available due to replication not running or, in the case of the gtmrecv.* control block base options, if not running on a non-primary instance where the gtmrecv.* control are available, a ZPEEKNOREPLINFO error is raised.

  • The JNL[REG] and JBL[REG] mnemonics and characteristics are defined by the running the GTMDefinedTypesInit.m utility, which produces a cross-index in the form:

    gtmtypfldindx(<structure-name>.<field-mnemonic>)=<n>

    where gtmtypes(<structure-name>,<n>,*) nodes contain the field characteristics

  • When $ZGBLDIR is set to a global directory specifying a replication instance and replication has started, the Replication Journal Pool for that instance becomes the source of data reported by $ZPEEK(). If a global directory does not specify a Replication Instance, the gtm_repl_instance environment variable determines the Instance for its replicated regions. The mnemonics GLF, GSL, JPC, NLREPL, and RIH require a jnlpool. $VIEW("JNLPOOL") returns the Instance for the current Replication Jounal Pool.

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