How can I make Perl and Python print each line of the program being executed?

Question

I know that bash -x script.sh will execute script printing each line before actual execution. How to make Perl and Python interpreters do the same?

Answer 1

Devel::Trace is the Perl analogue, the trace module is Python's.

Answer 2

python -m trace -t main.py

Test program:

main.py

from a import g
def f(i):
    g(i)
for i in range(3):
    f(i)

a.py

def g(i):
    print i

Output:

 --- modulename: main, funcname: <module>
main.py(1): from a import g
 --- modulename: a, funcname: <module>
a.py(1): def g(i):
main.py(2): def f(i):
main.py(4): for i in range(3):
main.py(5):     f(i)
 --- modulename: main, funcname: f
main.py(3):     g(i)
 --- modulename: a, funcname: g
a.py(2):     print i
0
main.py(4): for i in range(3):
main.py(5):     f(i)
 --- modulename: main, funcname: f
main.py(3):     g(i)
 --- modulename: a, funcname: g
a.py(2):     print i
1
main.py(4): for i in range(3):
main.py(5):     f(i)
 --- modulename: main, funcname: f
main.py(3):     g(i)
 --- modulename: a, funcname: g
a.py(2):     print i
2
main.py(4): for i in range(3):
 --- modulename: trace, funcname: _unsettrace
trace.py(80):         sys.settrace(None)

Tested on Ubuntu 16.10, Python 2.7.12.

Answer 3

Devel::DumpTrace was released in 2011 and has more features than Devel::Trace, such as evaluating variable values in the trace output.