firestring_estr_aestrcat(3) on Linux
The text 75f274a09e75, 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. The page shows this text now.
concatentate an estring onto another estring, expanding the destination if necessary