NAME
confstr —
get string-valued configurable
variables
SYNOPSIS
#include
<unistd.h>
size_t
confstr(int
name, char *buf,
size_t len);
DESCRIPTION
The
confstr()
function provides a method for applications to get configuration defined
string values.
The name argument specifies the system
variable to be queried. Symbolic constants for each name value are found in
the include file <unistd.h>.
The len argument specifies the size of the buffer
referenced by the argument buf. If
len is non-zero, buf is a
non-null pointer, and name has a value; up to
len - 1 bytes of the value are copied into the buffer
buf. The copied value is always NUL terminated.
The available values are as follows:
_CS_PATH- Return a value for the
PATHenvironment variable that finds all the standard utilities. _CS_V7_ENV- Return a space separated list of environment variable assignments (other
than
PATH) necessary for obtaining a shell environment compliant with IEEE Std 1003.1-2008 (“POSIX.1”). _CS_V6_ENV- Return a space separated list of environment variable assignments (other
than
PATH) necessary for obtaining a shell environment compliant with IEEE Std 1003.1-2001 (“POSIX.1”). _CS_POSIX_V7_THREADS_CFLAGS- Return the compiler flags for compiling objects in a program that uses multiple threads.
_CS_POSIX_V7_THREADS_LDFLAGS- Return the linker flags for linking an executable that uses multiple threads.
_CS_POSIX_V7_WIDTH_RESTRICTED_ENVS_CS_POSIX_V6_WIDTH_RESTRICTED_ENVS- Return a newline separated list of supported compilation environments in which none of the following types are wider than type long: blksize_t, cc_t, mode_t, nfds_t, pid_t, ptrdiff_t, size_t, speed_t, ssize_t, suseconds_t, tcflag_t, wchar_t, and wint_t.
_CS_POSIX_V7_ILP32_OFFBIG_CFLAGS_CS_POSIX_V7_ILP32_OFFBIG_LDFLAGS_CS_POSIX_V7_ILP32_OFFBIG_LIBS_CS_POSIX_V6_ILP32_OFFBIG_CFLAGS_CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS_CS_POSIX_V6_ILP32_OFFBIG_LIBS- If
sysconf(_SC_V7_ILP32_OFFBIG) returns a value greater than zero, return the compiler flags for compiling objects, the linker flags for linking an executable, or the linker arguments for additional libraries, respectively, for a compilation environment with 32-bit int, long, and pointer types and an off_t type that has a width of at least 64 bits. Otherwise, the result is unspecified. _CS_POSIX_V7_LP64_OFF64_CFLAGS_CS_POSIX_V7_LP64_OFF64_LDFLAGS_CS_POSIX_V7_LP64_OFF64_LIBS_CS_POSIX_V6_LP64_OFF64_CFLAGS_CS_POSIX_V6_LP64_OFF64_LDFLAGS_CS_POSIX_V6_LP64_OFF64_LIBS- If
sysconf(_SC_V7_LP64_OFF64) returns a value greater than zero, return the compiler flags for compiling objects, the linker flags for linking an executable, or the linker arguments for additional libraries, respectively, for a compilation environment with 64-bit int, long, pointer, and off_t types. Otherwise, the result is unspecified. _CS_POSIX_V7_LPBIG_OFFBIG_CFLAGS_CS_POSIX_V7_LPBIG_OFFBIG_LDFLAGS_CS_POSIX_V7_LPBIG_OFFBIG_LIBS_CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS_CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS_CS_POSIX_V6_LPBIG_OFFBIG_LIBS- If
sysconf(_SC_V7_LPBIG_OFFBIG) returns a value greater than zero, return the compiler flags for compiling objects, the linker flags for linking an executable, or the linker arguments for additional libraries, respectively, for a compilation environment with int, long, pointer, and off_t types that all have widths of at least 64 bits. Otherwise, the result is unspecified.
RETURN VALUES
If the call to confstr is not successful,
0 is returned and errno is set appropriately.
Otherwise, if the variable does not have a configuration defined value, 0 is
returned and errno is not modified. Otherwise, the
buffer size needed to hold the entire configuration-defined value is
returned. If this size is greater than the argument
len, the string in buf was
truncated.
ERRORS
The confstr function will fail if:
- [
EINVAL] - The value of the name argument is invalid.
SEE ALSO
STANDARDS
The confstr function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).
HISTORY
The confstr function first appeared in
4.4BSD.