File exist

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(redo; add race-condition warning.)
 
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-There are many ways to test if a file exists in Erlang. Here are some examples:+The function filelib:is_file/1 returns true if its argument refers to an existing file or directory. filelib:is_regular/1 more narrowly returns true on regular files.
 + 
<code> <code>
 +assert_config(Filename) ->
 + true = filelib:is_regular(Filename).
</code> </code>
-[[Category:CookBook]]+ 
 +Generally you should assume that files exist, are readable, etc. -- and gracefully handle your failures. You'll have to do this second part ''anyway'', as e.g. a file can be deleted after assert_config/1 succeeds and before your read_config/1 tries to open it.
 + 
 +[[Category:CookBook]] [[Category:FileRecipes]]

Current revision

The function filelib:is_file/1 returns true if its argument refers to an existing file or directory. filelib:is_regular/1 more narrowly returns true on regular files. 

assert_config(Filename) ->
    true = filelib:is_regular(Filename).

Generally you should assume that files exist, are readable, etc. -- and gracefully handle your failures. You'll have to do this second part anyway, as e.g. a file can be deleted after assert_config/1 succeeds and before your read_config/1 tries to open it.

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