pmParseUnitsStr(3) — Linux manual page


PMPARSEUNITSSTR(3)        Library Functions Manual        PMPARSEUNITSSTR(3)

NAME         top

       pmParseUnitsStr - parse units specification

C SYNOPSIS         top

       #include <pcp/pmapi.h>

       int pmParseUnitsStr(const char *string, struct pmUnits *out,
               double *outMult, char **errMsg);

       cc ... -lpcp

DESCRIPTION         top

       pmParseUnitsStr is designed to encapsulate the interpretation of a
       units (dimension and scale) specification in command line switches
       for use by the PCP client tools.

       This function expects to be called with the unit/scale specification
       as string.  This specification takes the general form produced by
       pmUnitsStr(3).  Briefly, the format allows /-separated divisor and
       dividend, each listing space-separated dimensions/scales along the
       space, time, and count axes.  There are also a few extra

       First, multiple equivalent sets of keywords are accepted for the time
       and space dimensions, insensitive to case.  For example,
       "microseconds", "microsecond", "microsec", "us" are considered
       synonymous, as are "kilobytes", "KB", "KiB", "kiloByte", and so on.

       Second, units may be offered in any order, e.g., ms kb count x 10^3
       or count x 10^3 kb ms.  They may not be repeated within the
       denominator or within the numerator.  Each scale/unit keyword may be
       immediately followed by positive or negative exponents, e.g., ^-4.

       Third, numerical scaling factors may be supplied.  These are factored
       together with implicit scale conversions into the final outMult

       The out and outMult values must both be allocated before calling
       pmParseUnitsStr(3).  If the conversion is successful, pmParseUnitsStr
       returns 0, and fills in out and outMult with the unit/scales defined
       by the input parameter.  If the argument strings could not be parsed,
       it returns a negative status code.

EXAMPLES         top

          │             string               │      out       │ outMult │
          │2 count                           │ {0,1,0,0,0,0}  │ 0.5     │
          │count / 7.5 nanosecond            │ {0,1,-1,0,0,0} │ 7.5     │
          │10 kilobytes / 2.5e2 count x 10^3 │ {1,-1,0,1,3,0} │ 25      │
          │millisecond / second^2            │ {0,0,-1,0,0,3} │ 1000    │
          │mib/s                             │ {1,0,-1,2,0,3} │ 1       │

BUGS         top

       For backward compatibility, this interface interprets several
       traditional computer science interpretations of space units
       incorrectly by the International System of Units (SI) standard.

       The accepted unit string - in either singular or plural form - and
       the pmParseUnitsStr interpretation for each are: megabyte(mebibyte),
       gigabyte(gibibyte), terabyte(tebibyte), petabyte(pebibyte),
       exabyte(exbibyte), zettabyte(zebibyte) and yottabyte(yobibyte).

RETURN VALUE         top

       A zero status indicates success.  A negative status indicates an
       error, in which case the errMsg pointer will contain a textual error
       message, which the caller should later free(3).

SEE ALSO         top

       PMAPI(3), pmUnitsStr(3), pmConvScale(3), and pmLookupDesc(3).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at ⟨⟩.
       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
       Git repository ⟨⟩ on
       2020-09-18.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-09-18.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Performance Co-Pilot                 PCP                  PMPARSEUNITSSTR(3)

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