{"id":25030,"date":"2015-12-10T14:27:11","date_gmt":"2015-12-10T12:27:11","guid":{"rendered":"https:\/\/mamchenkov.net\/wordpress\/?p=25030"},"modified":"2015-12-10T14:30:31","modified_gmt":"2015-12-10T12:30:31","slug":"weird-php-error-output-bug","status":"publish","type":"post","link":"https:\/\/mamchenkov.net\/wordpress\/2015\/12\/10\/weird-php-error-output-bug\/","title":{"rendered":"Weird PHP error output bug"},"content":{"rendered":"\n

We came across this PHP bug<\/a> at work today. \u00a0But before you go and read it, let me show you a use case. \u00a0See, if you can spot the problem.<\/p>\n

We had a cron job script which looked something like this (shortened for clarity):<\/p>\n

\r\n#!\/bin\/bash\r\n\r\n# ... a bunch of stuff here ... \r\n\r\ndate && echo "Updating products"\r\nphp updateProducts.php 1>\/dev\/null\r\n\r\nif [ "$?" -ne "0" ]\r\nthen\r\n  date && echo "Updating products failed"\r\n  exit 1\r\nfi\r\n\r\n# ... more stuff here ...\r\n<\/pre>\n
Crystal clear, no? Output a time stamp and a log message, run the product update, redirecting all normal output to standard output, and then check if the script finished fine. If not, print the time stamp and log message and exit with non-zero status code.<\/p>\n
We use similar code snippets all over the place, and they work fine. \u00a0This particular one was a new addition. \u00a0So the cron job ran and “Updating products failed<\/em>” part happened. \u00a0Weird. \u00a0 The PHP script in question has plenty of logging in it, but nothing was logged. \u00a0So we added more logs. \u00a0And then some more logs. \u00a0And even more logs. \u00a0Until it became obvious that something else is wrong, because even the first line of the script, which was now a logging action, wasn’t triggered.<\/p>\n
After a rather lengthy troubleshooting session we noticed that the updateProducts.php file was in fact named udpateProducts.php. \u00a0A simple typo in the file name. \u00a0But shouldn’t that be printed out into the error output?<\/p>\n
Let’s check:<\/p>\n
\r\n$ php no_such_file.php\r\nCould not open input file: no_such_file.php\r\n$ php no_such_file.php 1>\/dev\/null\r\n$\r\n<\/pre>\n
Huh? Where’s my error? It’s gone. \u00a0 That’s because if you are as used to the command line as I am, you’d expect PHP to output to STDERR. \u00a0But PHP is much smarter than that. \u00a0It has a whole slew of configuration options in regards to error output. \u00a0In this case, in particular, you need to check the values of display_errors<\/strong> and error_log<\/strong> configuration variables. \u00a0The bug report describes a Debian machine, while I tested it on Fedora, CentOS, and Amazon AMI.<\/p>\n
\r\n$ php -i | egrep '(display_errors|error_log)'\r\ndisplay_errors => Off => Off\r\nerror_log => no value => no value\r\n<\/pre>\n
Now it’s not much of a mystery. \u00a0But things like that can easily make you pull some hair out. \u00a0Hopefully, this gets some attention.<\/p>\n\n","protected":false},"excerpt":{"rendered":"\n
We came across this PHP bug at work today. \u00a0But before you go and read it, let me show you a use case. \u00a0See, if you can spot the problem. We had a cron job script which looked something like this (shortened for clarity): #!\/bin\/bash # … a bunch of stuff here … date && … Continue reading Weird PHP error output bug<\/span><\/a><\/p>\n\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"Weird PHP error output bug #WebDev #PHP","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false,"_links_to":"","_links_to_target":""},"categories":[1,18,62,1334],"tags":[38,1330],"keyring_services":[],"class_list":["post-25030","post","type-post","status-publish","format-standard","hentry","category-general","category-programming","category-technology","category-web-work","tag-php","tag-web-development"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t