The confstr() function provides a method for applications to get configuration-defined string values. Its use and purpose are similar to the sysconf(3C) function, but it is used where string values rather than numeric values are returned.

The name argument represents the system variable to be queried.

If len is not 0, and if name has a configuration-defined value, confstr() copies that value into the len-byte buffer pointed to by buf. If the string to be returned is longer than len bytes, including the terminating null, then confstr() truncates the string to len-1 bytes and null-terminates the result. The application can detect that the string was truncated by comparing the value returned by confstr() with len.

If len is 0, and buf is a null pointer, then confstr() still returns the integer value as defined below, but does not return the string. If len is 0 but buf is not a null pointer, the result is unspecified.

The confstr() function supports the following values for name, defined in <unistd.h>, for both SPARC and IA:

_CS_LFS64_CFLAGS

If _LFS64_LARGEFILE is defined in <unistd.h>, this value is the set of initial options to be given to the cc and c89 utilities to build an application using the Large File Summit transitional compilation environment (see lfcompile64(5)).

_CS_LFS64_LDFLAGS

If _LFS64_LARGEFILE is defined in <unistd.h>, this value is the set of final options to be given to the cc and c89 utilities to build an application using the Large File Summit transitional compilation environment (see lfcompile64(5)).

_CS_LFS64_LIBS

If _LFS64_LARGEFILE is defined in <unistd.h>, this value is the set of libraries to be given to the cc and c89 utilities to build an application using the Large File Summit transitional compilation environment (see lfcompile64(5)).

_CS_LFS64_LINTFLAGS

If _LFS64_LARGEFILE is defined in <unistd.h>, this value is the set of options to be given to the lint utility to check application source using the Large File Summit transitional compilation environment (see lfcompile64(5)).

_CS_LFS_CFLAGS

If _LFS_LARGEFILE is defined in <unistd.h>, this value is the set of initial options to be given to the cc and c89 utilities to build an application using the Large File Summit large file compilation environment for 32-bit applications (see lfcompile(5)).

_CS_LFS_LDFLAGS

If _LFS_LARGEFILE is defined in <unistd.h>, this value is the set of final options to be given to the cc and c89 utilities to build an application using the Large File Summit large file compilation environment for 32-bit applications (see lfcompile(5)).

_CS_LFS_LIBS

If _LFS_LARGEFILE is defined in <unistd.h>, this value is the set of libraries to be given to the cc and c89 utilities to build an application using the Large File Summit large file compilation environment for 32-bit applications (see lfcompile(5)).

_CS_LFS_LINTFLAGS

If _LFS_LARGEFILE is defined in <unistd.h>, this value is the set of options to be given to the lint utility to check application source using the Large File Summit large file compilation environment for 32-bit applications (see lfcompile(5)).

_CS_PATH

If the ISO POSIX.2 standard is supported, this is the value for the PATH environment variable that finds all standard utilities. Otherwise the meaning of this value is unspecified.

_CS_XBS5_ILP32_OFF32_CFLAGS

If sysconf(_SC_XBS5_ILP32_OFF32) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of initial options to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_XBS5_ILP32_OFF32_LDFLAGS

If sysconf(_SC_XBS5_ILP32_OFF32) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of final options to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_XBS5_ILP32_OFF32_LIBS

If sysconf(_SC_XBS5_ILP32_OFF32) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_XBS5_ILP32_OFF32_LINTFLAGS

If sysconf(_SC_XBS5_ILP32_OFF32) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of options to be given to the lint utility to check application source using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_XBS5_ILP32_OFFBIG_CFLAGS

If sysconf(_SC_XBS5_ILP32_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of initial options to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_XBS5_ILP32_OFFBIG_LDFLAGS

If sysconf(SC_XBS5_ILP32_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of final options to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_XBS5_ILP32_OFFBIG_LIBS

If sysconf(_SC_XBS5_ILP32_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the cc and c89 utilities to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_XBS5_ILP32_OFFBIG_LINTFLAGS

If sysconf(_SC_XBS5_ILP32_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of options to be given to the lint utility to check an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

The confstr() function supports the following values for name, defined in <unistd.h>, for SPARC only:

_CS_XBS5_LP64_OFF64_CFLAGS

If sysconf(_SC_XBS5_LP64_OFF64) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of initial options to be given to the cc and c89 utilities to build an application using a programming model with 64-bit int, long, pointer, and off_t types.

_CS_XBS5_LP64_OFF64_LDFLAGS

If sysconf(_SC_XBS5_LP64_OFF64) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of final options to be given to the cc and c89 utilities to build an application using a programming model with 64-bit int, long, pointer, and off_t types.

_CS_XBS5_LP64_OFF64_LIBS

If sysconf(_SC_XBS5_LP64_OFF64) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the cc and c89 utilities to build an application using a programming model with 64-bit int, long, pointer, and off_t types.

_CS_XBS5_LP64_OFF64_LINTFLAGS

If sysconf(_SC_XBS5_LP64_OFF64) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of options to be given to the lint utility to check application source using a programming model with 64-bit int, long, pointer, and off_t types.

_CS_XBS5_LPBIG_OFFBIG_CFLAGS

If sysconf(_SC_XBS5_LPBIG_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of initial options to be given to the cc and c89 utilities to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_XBS5_LPBIG_OFFBIG_LDFLAGS

If sysconf(_SC_XBS5_LPBIG_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of final options to be given to the cc and c89 utilities to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_XBS5_LPBIG_OFFBIG_LIBS

If sysconf(_SC_XBS5_LPBIG_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the cc and c89 utilities to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_XBS5_LPBIG_OFFBIG_LINTFLAGS

If sysconf(_SC_XBS5_LPBIG_OFFBIG) returns -1 the meaning of this value is unspecified. Otherwise, this value is the set of options to be given to the lint utility to check application source using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

If name has a configuration-defined value, the confstr() function returns the size of buffer that would be needed to hold the entire configuration-defined value. If this return value is greater than len, the string returned in buf is truncated.

If name is invalid, confstr() returns 0 and sets errno to indicate the error.

If name does not have a configuration-defined value, confstr() returns 0 and leaves errno unchanged.

The confstr() function will fail if:

EINVAL

The value of the name argument is invalid.

See attributes(5) for descriptions of the following attributes:

pathconf(2), sysconf(3C), attributes(5), lfcompile(5), lfcompile64(5)