DOKK / manpages / debian 10 / pcp / pmcpp.1.en
PMCPP(1) General Commands Manual PMCPP(1)

pmcpp - simple preprocessor for the Performance Co-Pilot

pmcpp [-Prs] [-D name[=value] ...] [-I dir ...] [infile]

pmcpp provides a very simple pre-processor originally designed for manipulating Performance Metric Name Space (PMNS) files for the Performance Co-Pilot (PCP), but later generalized to provide conditional blocks, include file processing, in-line shell command execution and macro substitution for arbitrary files. It is most commonly used internally to process the PMNS file(s) after pmLoadNameSpace(3) or pmLoadASCIINameSpace(3) is called and to pre-process the configuration files for pmlogger(1).

Input lines are read from infile (or standard input if infile is not specified), processed and written to standard output.

All C-style comments of the form /* ... */ are stripped from the input stream.

There are no predefined macros for pmcpp although macros may be defined on the command line using the -D option, where name and value must follow the same rules as described below for the #define directive.

pmcpp accepts the following directives in the input stream (like cpp(1)):

  • #include "filename"
    or
    #include <filename>
    In either case the directory search path for filename tries filename first, then the directory for the command line infile (if any), followed by any directories named in -I command line arguments, and finally the $PCP_VAR_DIR/pmns directory (the latter is for backwards compatibility with earlier versions of pmcpp and the implied used from pmLoadASCIINameSpace(3)). #include directives may be nested, up to a maximum depth of 5.
  • #shell "command"
    or
    #shell 'command'
    The shell command will be executed and the standard output is inserted into the stream of data to be processed by pmcpp. Functionally this is similar to a #include directive, except input lines are read from a command rather than a file. The #shell directive is most useful for including or excluding #define or #undef directives based on run-time logic in the command.
  • #define name value
    or
    #define name "value"
    or
    #define name 'value'
    Defines a value for the macro name which must be a valid C-style name, so leading alphabetic or underscore followed by zero or more alphanumerics or underscores. value is optional (and defaults to an empty string). There is no character escape mechanism, but either single quotes or double quotes may be used to define a value with special characters or embedded horizontal white space (no newlines).
  • #undef name
    Removes the macro definition, if any, for name.
  • #ifdef name
    ...
    #endif
    or
    #ifndef name
    ...
    #endif
    The enclosing lines will be stripped or included, depending if the macro name is defined or not.
  • #else
    Within a #ifdef or #ifndef block, #else may be used to delimit lines to be included if the preceding ``if'' condition is false.

Macro substitution is achieved by breaking the input stream into words separated by white space or characters that are not valid in a macro name, i.e. not alphanumeric and not underscore. Each word is checked and if it matches a macro name, the word is replaced by the macro value, otherwise the word is unchanged.

There is generally one output line for each input line, although the line may be empty if the text has been stripped due to the handling of comments or conditional directives. When there is a change in the input stream, an additional output line is generated of the form:

# lineno "filename"

to indicate the following line of output corresponds to line number lineno of the input file filename.

The -P argument suppresses the generation of these linemarker lines.

The -s argument changes the expected input style from C-like to shell-like (where # is a comment prefix). This forces the following changes in pmcpp behaviour:

  • The control prefix character changes from # to %, so %include for example.
  • No comment stripping is performed.

To provide finer control of macro expansion, the -r option restricts macro substitution to words that match the patterns #name or #{name} or if -s is specified, then %name or %{name}. In this mode, the macro name alone in the input stream will never be expanded, however in control lines (like #ifdef) the macro name should appear alone with out the prefix character or the curly braces (refer to the EXAMPLES below).

Important cpp(1) features that are not supported by pmcpp include:

  • Macros with parameters - the pmcpp macros support only parameterless string substitution.
  • #if expr
    ...
    #endif
  • Nested use of #ifdef or #ifndef.
  • Stripping C++ style comments, as in // comment.
  • Error recovery - the first error encountered by pmcpp will be fatal.
  • cpp(1) command line options like -o, -W, -U, and -x.

Command: pmcpp
Input Output
# 1 "<stdin>"
#define MYDOMAIN 27
root { root {
foo MYDOMAIN:0:0 foo 27:0:0
} }

For the following examples, the file frequencies contains the lines:



%define dk_freq 1minute
%define cpu_freq '15 sec'

Command: pmcpp -rs
Input Output
# get logging frequencies # get logging frequencies
# e.g. dk_freq macro # e.g. dk_freq macro
%include "frequencies"
log mandatory on %dk_freq { log mandatory on 1minute {
disk.dev disk.dev
} }
# note no % for want_cpu here # note no % for want_cpu here
%ifdef want_cpu
%define cpu_pfx 'kernel.all.cpu.'
log mandatory on %cpu_freq {
%{cpu_pfx}user
%{cpu_pfx}sys
}
%endif

Command: pmcpp -rs -Dwant_cpu
Input Output
# get logging frequencies # get logging frequencies
# e.g. dk_freq macro # e.g. dk_freq macro
%include "frequencies"
log mandatory on %dk_freq { log mandatory on 1minute {
disk.dev disk.dev
} }
# note no % for want_cpu here # note no % for want_cpu here
%ifdef want_cpu
%define cpu_pfx 'kernel.all.cpu.'
log mandatory on %cpu_freq { log mandatory on 15 sec {
%{cpu_pfx}user kernel.all.cpu.user
%{cpu_pfx}sys kernel.all.cpu.sys
} }
%endif

Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).

cpp(1), pmLoadASCIINameSpace(3), pmLoadNameSpace(3), pmns(5), pcp.conf(5) and pcp.env(5).

Performance Co-Pilot