Python command line write to file

Output to command line and write to file in python script

But you can use to do so. Be aware, that the command must be passed to the method as a list of commands / parameters: Solution 1: As others have already pointed out the difference between (overwrite) and (append) redirection operators, i am going to give couple of solutions. And please do not use the pipe to write multiple commands in one line, which would redirect the first command’s output ( ) to the second command’s input ( ).

Output to command line and write to file in python script

open a file and write your string in it:

 with open('my_file' , 'w') as f: f.write('your_string') 

and if you want to redirect your output to a file use > in terminal after invoke the .py file :

$~ python my_file.py > save_file.txt 

Can’t output lmod commands to text file using python in hpc, Lmod (and Environment Modules) send their output to STDERR, not STDOUT so I think you should just modify your script to:

How to store command output in file

You can use > to write the command line output to a file as follows:

import os os.system('ls -al > output.txt') 

os.system(«ls -al») won’t return the output you normally see in the shell but only the return code. 0 if the command was executed successfully, 1 if not, etc. Read more about this here.

But you can use subprocess.check_output() to do so. Be aware, that the command must be passed to the method as a list of commands / parameters:

import subprocess output = subprocess.check_output(["ls", "-al"]) open("output.txt", "w").write(output) 

How to write script output to file and command-line?, I am using Mac OS X 10.6.4. Edit I am using print for output in my script. python unix command-line.

Write the output of multiple sequential commands to a text file

As others have already pointed out the difference between > (overwrite) and >> (append) redirection operators, i am going to give couple of solutions.

You can use the command grouping <> feature of bash to send the output of all the commands in a single file :

( sha1sum foo.txt ;sha512sum foo.txt ;md5sum foo.txt ) >checksum.txt 

You need to use the append redirector >> instead of > for the subsequent commands e.g.

sha1sum zeromq-4.1.2.tar.gz > sha.txt md5sum zeromq-4.1.2.tar.gz >> sha.txt sha512sum zeromq-4.1.2.tar.gz >> sha.txt 

See the Appending Redirected Output section of the bash manual page ( man bash ).

The > redirector writes the command’s output ( stdout , not stderr — you use 2> for that) to the file specified after it. If it already exists, the file will get overwritten.

This behaviour is useful for the first of your commands: if there’s an existing file, it should get deleted and replaced with the new one.

However, as you need to append all further outputs instead of replacing the previous ones, you need to use the append-redirector >> . This will create a file if it does not exist yet, but appends the redirected output to the file, if it already exists.

And please do not use the pipe | to write multiple commands in one line, which would redirect the first command’s output ( stdout ) to the second command’s input ( stdin ).

You can use the semicolon ( ; ) to just tell bash to execute one command after the other, as if it was a script file. If a command fails (return code is not 0), the remaining commands still get executed.

Or you may chose the logic operators AND ( && ) or OR ( || ):
If you use && to connect two commands, the second one will only be executed, if the first one succeeds (return code is 0). If it fails, none of the following commands will run.
The || however only runs the second command if the first one failed (return code is not 0)!

So in your case I would recommend you to use the semicolon:

md5sum firefox.tar.gz > sha.txt ; sha1sum firefox.tar.gz >> sha.txt ; sha512sum firefox.tar.gz >> sha.txt 

How to Create a Text File Using the Command Line in Linux, As simple as that, just type the word touch followed by the name of the file you like to give it, and Voila! you have created an empty text file

Python Redirect command output to log file [duplicate]

You have this previously answered question if you want to redirect to file: Redirect stdout to a file in Python?

The following example for redirecting to a memory string (from python docs):

import io from contextlib import redirect_stdout f = io.StringIO() with redirect_stdout(f): help(pow) s = f.getvalue() 

And the latter example (if you just want to suppress the sys.stdout), trying to understand how it works: print will try to access the write method of sys.stdout , so I will just replace it with a class that has a write method that does nothing.

>>> class R: . def write(*args, **kwargs): . pass >>> from contextlib import redirect_stdout >>> with redirect_stdout(R()): . print('ciao') 

How to store command output in file, You can use > to write the command line output to a file as follows: import os os.system(‘ls -al > output.txt’).

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3 Ways to Write Text to a File in Python

If you are interested in writing text to a file in Python, there is probably many ways to do it. Here is three ways to write text to a output file in Python. The first step in writing to a file is create the file object by using the built-in Python command “open”. To create and write to a new file, use open with “w” option. The “w” option will delete any previous existing file and create a new file to write.

# open a (new) file to write outF = open("myOutFile.txt", "w")

If you want to append to an existing file, then use open statement with “a” option. In append mode, Python will create the file if it does not exist.

# open a file to append outF = open("myOutFile.txt", "a")

Once you have created the file object in write/append mode, you can write text in multiple ways. Let us say we have the text that we want to write is in a list “textList”.

textList = ["One", "Two", "Three", "Four", "Five"]

We can write this list to a file either line by line or write all lines at once.

Writing One Line at a Time to a File in Python Using write()

Let us create new file by creating the file object “outF” using “w” option as before. To write line by line, we loop through the textList and get each element and write it to the file.

outF = open("myOutFile.txt", "w") for line in textList: # write line to output file outF.write(line) outF.write("\n") outF.close()

Note that the elements in the “textList” does not have a new line character “\n”. Therefore, we added that while writing to the file. Otherwise, all five elements will be in a single line in the output file. Also note outF.close() at the end. close() method closes the access to the file. It is a good practice to use the close() method to close a file, once we are done with a file.

Writing One Line at a Time to a File in Python Using “print”

Another way to write one line at a time to a file in Python is to use the print statement. Instead of printing a statement to the scree, we redirect to the output file object.

outF = open("myOutFile.txt", "w") for line in textList: print >>outF, line outF.close()

writelines(): Writing All The Lines at a Time to a File in Python

Python also has a method that can write all lines at the same time to a file. Python’s “writelines()” method takes a list of lines as input and writes to a file object that is open with write/append access. For example to write our list of all line “all_lines”, using “writelines().

outF = open("myOutFile.txt", "w") outF.writelines(all_lines) outF.close()

We can also make our lives easier without writing file.close() statement by using with statement to write to a file. For example,

with open(out_filename, 'w') as out_file: .. .. .. parsed_line out_file.write(parsed_line)

If you are interested in reading from a text file, check Three ways to read a text file line by line in python.

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