Python: Join consecutive lines if separated by backslash and remove backslash also

Question

I have got a file containing shell commands. Each command may be split across multiple lines (using backslash at end):
e.g.

  cmd1 -opt1   
    -opt2 val2    
    -opt3 val3 val4

I want to join consecutive lines if separated by backslash at end. i also want to remove backslash after joining.

The problem is similar to:
Input:
[‘abc’, ‘def \’, ‘ghi \’, ‘jkl’ , ‘yyy \’, ‘zzz’]
output:
[‘abc’, ‘def ghi jkl’, ‘yyy zzz’]

is looping through the list only solution ?

with open("cmd", "r") as fp:
    cmd = ""
    cont = False
    list = []
    for line in fp:
        line = line.rstrip("n")
        if line.endswith('\'):
            line = line[:-1]
            if cont:
                cmd = cmd + line
                continue
            if cmd:
                list.append(cmd)
            cmd = line
            cont = True
        else:
            if cont:
                cmd = cmd + line
                if cmd:
                    list.append(cmd)
                cmd = ""
                continue
            cont = False
    print(list)

Asked By: Deepak Yadav

||

Source

Answer 1

is looping through the list only solution ?

You will have to assess each line for a concatenation indicator and append the next line. Yes, you’ll have to loop through.

Here’s a function to do it using a generator so the whole input doesn’t need to be in memory.

>>> sample = ['abc', 'def \', 'ghi \', 'jkl' , 'yyy \', 'zzz']
>>>
>>> def join_lines(sequence):
...   i = iter(sequence)
...   buff = ''
...   try:
...     while True:
...       line = i.next()
...       if line.endswith('\'):
...         line = line[:-1]
...         buff += line
...       else:
...         if buff:
...           buff += line
...           yield buff
...           buff = ''
...         else:
...           yield line
...   except StopIteration:
...     if buff:
...       yield buff
...
>>> print sample
['abc', 'def \', 'ghi \', 'jkl', 'yyy \', 'zzz']
>>> print list(join_lines(sample))
['abc', 'def ghi jkl', 'yyy zzz']

Answered By: MattH

Answer 2

cmd = ['abc', 'def \', 'ghi \', 'jkl' , 'yyy \', 'zzz']

res = "n".join(cmd).replace("\\n", "").splitlines()

print(res)

=> ['abc', 'def ghi jkl', 'yyy zzz']

Answered By: Clodion

Answer 3

This can be way to join lines and iterate over such a file:

with open("cmd", "r") as fp:
    data = fp.read()
    lines = data.replace("\n", "").splitlines()
    lines = [ x + "n" for x in lines ]
    for line in lines:
        print(line)

Answered By: Deepak Yadav

Python: Join consecutive lines if separated by backslash and remove backslash also

Question:

Answers: