3.13 linecache -- Random access to text lines

The linecache module allows one to get any line from any file, while attempting to optimize internally, using a cache, the common case where many lines are read from a single file. This is used by the traceback module to retrieve source lines for inclusion in the formatted traceback.

The linecache module defines the following functions:

getline( filename, lineno)
Get line lineno from file named filename. This function will never throw an exception -- it will return '' on errors (the terminating newline character will be included for lines that are found).

If a file named filename is not found, the function will look for it in the module  search path, sys.path.

clearcache( )
Clear the cache. Use this function if you no longer need lines from files previously read using getline().

checkcache( )
Check the cache for validity. Use this function if files in the cache may have changed on disk, and you require the updated version.

Example:

>>> import linecache
>>> linecache.getline('/etc/passwd', 4)
'sys:x:3:3:sys:/dev:/bin/sh\n'
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