libmtraceall is a wrapper around mtrace() that can be LD_PRELOAD'ed into the target process.
mtrace() is a GNU C Library feature that enables malloc() hooks to trace allocations and deallocation.
Environment variable MALLOC_TRACE must be defined and the mtrace() function must be called by the program for the hooks to be enabled.
It usually cumbersome to modify a target program to call mtrace(), so using a shared object, LD_PRELOAD'ed into the executable program, could be useful then.
But using the same filename in MALLOC_TRACE environment variable will lead to multiple program writing to the same file, overwriting each other.
libmtraceall takes care of generating an unique MALLOC_TRACE file name for each program it's preloaded into, so that mtrace() output is not overwritten.
Example:
$ make
$ LD_PRELOAD=./libmtraceall.so MALLOC_TRACE_ALL=mtraceall.out nm mtraceall.o
$ ls mtrace.out.*
mtraceall.out.1557930662.23814.eApkxw
The generated filenames are built from the filename prefix in MALLOC_TRACE_ALL variable, Unix epoch timestamp, process identifier (PID), and a random suffix to cope with exec()'ed program having the same PID (could also handle PID reusing).
BEWARE that a process calling exec() won't have a chance to call muntrace() (or exit()), so its output file could be truncated. In fact it's likely to be empty. It's usually harmless, as most process fork() before calling exec(). Anyway if the file was not truncated, mtrace would have shown many memory leak, so not having the file is quite expected.