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STRVARS(3pub) C Programmer's Manual STRVARS(3pub)


strvars - expand variables in string


#include <publib.h>
int strvars(char **res, const char *str, char *(*expand)(const char *));


strvars will replaces references to variables in the string str with the values of the variables. A reference to a variable is of the form $(foo) or $x (where x is a single character, but not $). A dollar sign is expressed in the string as $$, and will be converted to $ in the output. Memory for the expanded string is allocated dynamically, and *res is set to point to it.

The values of the variables are fetched using the function expand. It is given the name of the variable as its argument, and must return a pointer to the value, or NULL if that variable doesn't exist.


strvars will return 0 if successful, or NULL if an error occurred (malformed input string, result too big, or unknown variable).


To replace references to environment variables, one would the following.

#include <publib.h> #include <stdlib.h> char line[1024]; char *res; if (strvars(&res, line, getenv) == NULL)
errormsg(1, 0, "strvars failed"); printf("res = <%s>\n", res);


publib(3), getenv(3)


Lars Wirzenius (

C Programmer's Manual Publib