ctrsm(3) on Linux
The text 06a458bf9efe, as Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny), Debian 4.0 (Etch), Debian 3.1 (Sarge) shipped it.
solve one of the matrix equations op( A )*X = alpha*B, or X*op( A ) = alpha*B,