Determine function and file dependency of a shell script?

Question

I'm looking for a way of processing a shell script to determine:

1. which commands, scripts or functions are called in the script.
2. which files are accessed by the script (r or w) .

It doesn't need to recurse down through the dependencies, just list what it runs directly. I could probably write something that does this myself but it must have been done before ... I'm just not finding it.

Answer 1

You can use 'strace' to run a script and see everything the script and its subprocesses do, including looking for and opening files. For example:

$ cat foo.sh
#!/usr/bin/env bash

touch /tmp/foon
$ chmod +x foo.sh
$ strace -f -e execve,access,open,stat -o foo.trace ./foo.sh
$ cat foo.trace
32176 execve("./foo.sh", ["./foo.sh"], [/* 42 vars */]) = 0
32176 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
32176 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
32176 open("/usr/local/lib/tls/x86_64/libc.so.6", O_RDONLY) = -1 ENOENT (No such file or directory)
...
32176 execve("/bin/bash", ["bash", "./foo.sh"], [/* 42 vars */]) = 0
...
32177 execve("/usr/bin/touch", ["touch", "/tmp/foon"], [/* 41 vars */]) = 0
32177 open("/tmp/foon", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = 3
...
32176 --- SIGCHLD (Child exited) @ 0 (0) ---
$ 

I've trimmed a lot of the other activity going on there (opening system libraries; looking up locale data; and much more). Check out 'man strace' for details on what the options mean; -f, -o, and -e are the ones I use most often.