squid(8)

📦
version 7.7 · 4 versions
, in ubuntu resolute, ubuntu stonking

🌸 squid(8) — from the System Manager's Manual 🌸

okay bestie, sit down, because we're talking about squid 💅 and no she's not the sea creature, she's the HTTP web proxy caching server and she's iconic.

✨ NAME ✨

squid — HTTP web proxy caching server 🦋

✨ SYNOPSIS ✨

squid [-dhisrvzCFNRSVYX] [--foreground] [-l facility ] [-f config-file ]
      [-[au] port ] [-k signal ] [-n service-name ] [-O command-line ]

like. that's the whole vibe right there. lots of little letters. she contains multitudes 💖

✨ DESCRIPTION ✨

squid is a high-performance proxy caching server for web clients, and she handles FTP, ICAP, ICP, HTCP and HTTP data objects. no cap. and the way she does it?? unlike traditional caching software, Squid handles all requests in a single, non-blocking process. one process. main character energy fr fr 👑

Squid keeps meta data — and especially hot objects 🔥 — cached in RAM, caches DNS lookups, supports non-blocking DNS lookups, and implements negative caching of failed requests. so when something flops, she remembers it flopped. efficient queen.

She also supports SSL, extensive access controls, and full request logging ✨. And by using the lightweight Internet Cache Protocols ICP, HTCP or CARP, Squid caches can be arranged in a hierarchy or mesh for additional bandwidth savings. friendship bracelets but for servers 🫶

Squid consists of a main server program squid, some optional programs for custom processing and authentication, and some management and client tools. When squid starts up, it spawns a configurable number of helper processes, each of which can perform parallel lookups. This reduces the amount of time the cache waits for results. delegation!! we love to see it.

Squid is derived from the ARPA-funded Harvest Project. ancestral lore 🧚

listen up though — this manual page only lists the command line arguments. For details on how to configure Squid see the file /etc/squid/squid.conf.documented, the Squid wiki FAQ and examples at https://wiki.squid-cache.org/, or the configuration manual on the Squid home page http://www.squid-cache.org/Doc/config/

✨ OPTIONS ✨

every single flag, bestie. every one. 💅

  • -a port — Specify HTTP port number where Squid should listen for requests, in addition to any http_port specifications in squid.conf. so she listens there too, she's multitasking.
  • -C — Do not catch fatal signals. she's letting it ride 😭
  • -d level — Write debugging to stderr also. more tea, pls.
  • -f file — Use the given config-file instead of /etc/squid/squid.conf. And get this — if the file name starts with a ! or | then it is assumed to be an external command or command line. Can for example be used to pre-process the configuration before it is being read by Squid. To facilitate this Squid also understands the common #line notion to indicate the real source file. she speaks preprocessor, obviously ✨
  • -F — Don't serve any requests until store is rebuilt. patience era.
  • -h — Print help message. she's helpful, it's giving considerate 💖
  • -i — Install as a Windows Service (see -n option).
  • -k reconfigure | rotate | shutdown | interrupt | kill | debug | check | parse — Parse configuration file, then send signal to running copy (except -k parse) and exit. pick your poison, gorgeous.
  • -l facility — Use specified syslog facility. Implies -s. sneaky little implication 🌸
  • -n name — Specify Windows Service name to use for service operations, default is: Squid
  • -N — No daemon mode. she stays right here with you 🫶
  • --foreground — Parent process does not exit until its children have finished. It has no effect with -N which does not fork/exit at startup. important detail!! don't @ me.
  • --kid roleID — Play a given SMP kid process role, with a given ID. Do not use this option. It is meant for the master process use only. hands off bestie, that's grown folks' business 🚫
  • -O options — Set Windows Service Command line options in Registry.
  • -r — Remove a Windows Service (see -n option). bye girl 💀
  • -R — Do not set REUSEADDR on port.
  • -s — Enable logging to syslog. Also configurable in /etc/squid/squid.conf
  • -S — Double-check swap during rebuild. she's double checking. thorough queen.
  • -u port — Specify ICP port number (default: 3130), disable with 0. yes, zero. zero it out.
  • -v — Print version and build details.
  • -X — Force full debugging. all of it. every crumb.
  • -Y — Only return UDP_HIT or UDP_MISS_NOFETCH during fast reload.
  • -z — Create missing swap directories and other missing cache_dir structures, then exit. All cache_dir types create the configured top-level directory if it is missing. Other actions are type-specific. For example, ufs-based storage systems create missing L1 and L2 directories while Rock creates the missing database file.

This option does not enable validation of any present swap structures. Its focus is on creation of missing pieces. If nothing is missing, squid -z just exits. If you suspect cache_dir corruption, you must delete the top-level cache_dir directory before running squid -z. ⚠️ genuinely important ⚠️

By default, squid -z runs in daemon mode (so that configuration macros and other SMP features work as expected), returning control to the caller before cache_dirs are fully initialized. If run from init scripts or daemon managers, the caller often needs to wait for the initialization to complete before proceeding further. Use --foreground option to prevent premature exits. To disable daemon mode, use -N option. okay so those two flags are basically the whole plot twist here 🔥

✨ FILES ✨

Squid configuration files located in /etc/squid/:

  • squid.conf — The main configuration file. You must initially make changes to this file for squid to work. For example, the default configuration only allows access from RFC private LAN networks. Some packaging distributions block even that. (rude, honestly.)
  • squid.conf.default — Reference copy of the configuration file. Always kept up to date with the version of Squid you are using. Use this to look up the default configuration settings and syntax after upgrading. she keeps receipts ✨
  • squid.conf.documented — Reference copy of the configuration file. Always kept up to date with the version of Squid you are using. Use this to read the documentation for configuration options available in your build of Squid. The online configuration manual is also available for a full reference of options. see http://www.squid-cache.org/Doc/config/
  • msntauth.conf — The main configuration file for the Sample MSNT authenticator.
  • errorpage.css — CSS Stylesheet to control the display of generated error pages. Use this to set any company branding you need, it will apply to every language Squid provides error pages for. branding era 🎀

Some files also located elsewhere:

  • /usr/share/squid/mime.conf (mime_table) — MIME type mappings for FTP gatewaying
  • /usr/share/squid/errors — Location of Squid error pages and templates.

✨ AUTHOR ✨

Squid was written over many years by a changing team of developers and maintained in turn by Duane Wessels <duane@squid-cache.org>, Henrik Nordstrom <hno@squid-cache.org>, and Amos Jeffries <amosjeffries@squid-cache.org> — legends, all of them 👑

With contributions from many others in the Squid community. see CONTRIBUTORS for a full list of individuals who contributed code. see CREDITS for a list of major code contributing copyright holders. give them their flowers 💐

 * Copyright (C) 1996-2026 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.

✨ QUESTIONS ✨

Questions on the usage of this program can be sent to the Squid Users mailing list <squid-users@lists.squid-cache.org> — they're nice, go ask 🫶

✨ REPORTING BUGS ✨

Bug reports need to be made in English. See https://wiki.squid-cache.org/SquidFaq/BugReporting for details of what you need to include with your bug report.

Report bugs or bug fixes using https://bugs.squid-cache.org/

Report serious security bugs to Squid Bugs <squid-bugs@lists.squid-cache.org>

Report ideas for new improvements to the Squid Developers mailing list <squid-dev@lists.squid-cache.org>

like genuinely, if you found a security thing, tell them directly. that's not a group chat moment, that's an email moment 🔐

✨ SEE ALSO ✨

okay that's the whole thing bestie, you're officially Squid-literate 💖 that was the squid(8) page from the System Manager's Manual — go forth and proxy, and remember: caching is self-care 🌸✨🦋

📦 where this page comes from