$ strace php tias.php -e open,access 2>&1 | <a class="zem_slink freebase/en/grep" href="http://en.wikipedia.org/wiki/Grep" title="Grep" rel="wikipedia">grep foo.txt Sometimes a program refuses to read a file and you’re not sure why. You may have display_errors turned off for <a class="zem_slink freebase/en/php" href="http://www.php.net/" title="PHP" rel="homepage">PHP or something. In this example, fopen(’/var/www/test/foo.txt’) was called but doesn’t have read access to foo.txt.
Strace can tell you what went wrong. E.g., if php doesn’t have read access to the file, strace will say ”EACCESS (Permission denied)”.
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