{"id":66,"date":"2009-02-05T20:57:01","date_gmt":"2009-02-05T20:57:01","guid":{"rendered":"http:\/\/blog.danplanet.com\/wordpress\/?p=66"},"modified":"2009-02-05T20:57:01","modified_gmt":"2009-02-05T20:57:01","slug":"running-strerror-from-the-shell","status":"publish","type":"post","link":"https:\/\/www.danplanet.com\/blog\/2009\/02\/05\/running-strerror-from-the-shell\/","title":{"rendered":"Running strerror() from the shell"},"content":{"rendered":"

Reasonably often, I have a need to convert an errno variable to its string error message right at the shell.\u00a0 This seems to come up relatively often in kernel development, but occasionally elsewhere.\u00a0 Where I can, I usually just go for a printf(“Error: %mn”\"Smilie:<\/font> or printf(“Error: %sn”, strerror(foo))<\/font> directly in the debug statement I’m adding.\u00a0 However, %m<\/font> doesn’t work in the kernel and occasionally I either want or have to avoid recompiling something that just prints the integer value.\u00a0 Chasing the header file chain to figure out what a given error code is can be time consuming and silly, but I’ve done it.<\/p>\n

Recently, I’ve been trying to notice when I do stupid things repetitively and take the time to write a helper script or shell alias to prevent wasting effort the next time I need to do a particular task.\u00a0 I have a collection of shell aliases, but I also keep a ~\/bin<\/font> directory with helper scripts for things that fit that mold better.\u00a0 To solve my errno issue, I wrote the following today and stored it in ~\/bin\/perror<\/font>:<\/p>\n

\n

#!\/usr\/bin\/python<\/p>\n

import os
import sys<\/p>\n

for i in sys.argv[1:]:
\u00a0\u00a0\u00a0 i = abs(int(i))<\/p>\n

\u00a0\u00a0\u00a0 print “%3i: %s” % (i, os.strerror(i))
<\/font><\/p>\n<\/blockquote>\n

It could probably be done smaller in a shell alias that calls perl or something, but oh well.\u00a0 This is pretty handy so I can quickly get a couple of values:<\/p>\n

\n

% perror 111 22
111: Connection refused
\u00a022: Invalid argument<\/font><\/p>\n<\/blockquote>\n

I’ve already used it several times today, so it was definitely worth the 2 minutes it took to codify it. <\/p>\n","protected":false},"excerpt":{"rendered":"

Reasonably often, I have a need to convert an errno variable to its string error message right at the shell.\u00a0 This seems to come up relatively often in kernel development, but occasionally elsewhere.\u00a0 Where I can, I usually just go … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"class_list":["post-66","post","type-post","status-publish","format-standard","hentry","category-codemonkeying"],"yoast_head":"\nRunning strerror() from the shell - Right Angles<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.danplanet.com\/blog\/2009\/02\/05\/running-strerror-from-the-shell\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Running strerror() from the shell - 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