dthain / envtrace

Trace what environment variables are used by an application.

envtrace - trace environment lookups

Complex programs can often be difficult to debug when they make use of environment variables: it's not at all obvious what variables a program may access, or what value they had at the time of access.

envtrace allows you to run a program and observe how it accesses the environment. First, build the software:

make

And then use envtrace as a wrapper around your program:

./envtrace ps

The results are placed into env.trace in the current working directory. Each line in this file gives the program name, variable name, whether the lookup succeeded, and the value returned:

ps COLUMNS HIT 120
ps LINES MISS
ps PS_PERSONALITY MISS
ps I_WANT_A_BROKEN_PS MISS
...

This program is a 15-minute hack written to explore an idea and see if it turns up any surprises. In fact, this README is already longer than the source code of the program. This has been tested on RHEL7 and might work on other Linuxes. It probably needs some adjustment to work on other Unixes. Please set your expectations appropriately.

Douglas Thain [e-mail]