--- title: TIL: Number in man page titles (e.g. sleep(3)) | daily.dev description: A short TIL explaining what the numbers in Linux man page titles mean (e.g., sleep(3), read(2)). Section 1 covers executable programs/shell commands, section 2... canonical: https://daily.dev/posts/til-number-in-man-page-titles-e-g-sleep-3--kcvhscujr twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: TIL: Number in man page titles (e.g. sleep(3)) | daily.dev og:description: A short TIL explaining what the numbers in Linux man page titles mean (e.g., sleep(3), read(2)). Section 1 covers executable programs/shell commands, section 2... og:url: https://daily.dev/posts/til-number-in-man-page-titles-e-g-sleep-3--kcvhscujr og:image: https://api.daily.dev/og/posts/KCVhSCujR.png og:image:alt: TIL: Number in man page titles (e.g. sleep(3)) og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # TIL: Number in man page titles (e.g. sleep(3)) **[Hacker News](https://daily.dev/sources/hn)** · 2 min read · 3 upvotes · 1 comments ## Summary A short TIL explaining what the numbers in Linux man page titles mean (e.g., sleep(3), read(2)). Section 1 covers executable programs/shell commands, section 2 covers system calls, and section 3 covers library calls. The post was prompted by a code review comment pointing out that basename is a libc library call (man 3), not a syscall (man 2). Also briefly covers letter suffixes like 'p' for POSIX pages and 'x' for X documentation. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@ralsei** · 0 upvotes > Oh this is neat, TIL for me too. ## Similar posts on daily.dev - [Why Linux experts are ditching Man pages for this simple tool](https://daily.dev/posts/why-linux-experts-are-ditching-man-pages-for-this-simple-tool-jbwbv3wwr) · All Things Open · 6 upvotes · 3 comments - [How a System Call Actually Works in Linux](https://daily.dev/posts/how-a-system-call-actually-works-in-linux-kj1mr4pdv) · freeCodeCamp · 1 upvotes · 0 comments - [Notes on clarifying man pages](https://daily.dev/posts/notes-on-clarifying-man-pages-ggngx7ieq) · Julia Evans · 4 upvotes · 0 comments --- Tags: [#linux](https://daily.dev/tags/linux) [View this post on daily.dev](https://daily.dev/posts/til-number-in-man-page-titles-e-g-sleep-3--kcvhscujr) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"TIL: Number in man page titles (e.g. sleep(3))","url":"https://daily.dev/posts/til-number-in-man-page-titles-e-g-sleep-3--kcvhscujr","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/til-number-in-man-page-titles-e-g-sleep-3--kcvhscujr"},"datePublished":"2026-04-06T14:34:04.710Z","dateModified":"2026-04-06T14:34:20.432Z","description":"A short TIL explaining what the numbers in Linux man page titles mean (e.g., sleep(3), read(2)). 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