Tail a file from ssh and mirror to a local file

Question

I'm developing on a RedHat Linux server and the Python version installed is the 2.6. I have a Python script that have to replace a string in a file .sql. Each time I run the Python script I pass a different argument that must replace the oldest value inside the same .sql file.

File .sql has a content like this:

SELECT * FROM MY_TABLE WHERE 1=1
AND '1234567890' BETWEEN START_VALUE AND END_VALUE
AND JOB = 'EMPLOYEE';

I don't want to use some temporary files for the elaboration, I should have to read the .sql and modify it contextually.

I searched on other posts but I've never found the final solution. I tried to use re.sub but I didn't find how to make the replacement in effect inside .sql.

Solution 1

Yes, you can usee tee for that:

ssh  -t remotebox "tail -f /var/log/remote.log" | tee -a /var/log/local.log

This way output will be printed on both stdout and copied over into /var/log/local.log on the system you are running ssh command from.

Solution 2

Just redirect the stdout.

ssh -t remotebox tail -f /var/log/remote.log > local.log

To append to local.log:

ssh -t remotebox tail -f /var/log/remote.log >> local.log

This will write to the local server.

The remote server would only be written to if you include the redirect in the quotes:

ssh -t removebox "tail -f /var/log/remote.log >> remote.log"

Comments

[SET]

is it possible to do the opposite - to tail local file to the remote server over ssh?

[MDR]

For MySQL it might have been SET @END_VALUE = ... rather than DECLARE @END_VALUE = ...

[Alessandro Barca]

sorry, i forgot to explain that the string i want to replace is the '1234567890' but this works as well. I found a solution while you were answering but it is like your. Read the file with file.read() function that return a 'str' type. Then using re.sub() to replace the string and finally re-write the file with the new value. My issue was to understand the difference between reading a file line-by-line or as a single block (string). Now I understood better. Thank you very much.