{"id":78680,"date":"2026-05-30T23:22:30","date_gmt":"2026-05-30T23:22:30","guid":{"rendered":"http:\/\/bangla.sitestree.com\/?p=78680"},"modified":"2026-05-30T23:22:31","modified_gmt":"2026-05-30T23:22:31","slug":"linux-regular-permissions-symbolic-numeric-vs-acl","status":"publish","type":"post","link":"http:\/\/bangla.sitestree.com\/?p=78680","title":{"rendered":"Linux: Regular Permissions (symbolic\/numeric) vs ACL"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Linux has <strong>two main permission layers<\/strong>:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>1. Traditional permissions: user \/ group \/ others  (UGO)\n2. ACL permissions: extra permission rules for specific users\/groups\n<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\">1. Traditional UGO permissions<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">UGO means:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>u = user owner\ng = group owner\no = others\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Example:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>chmod ugo+x script.sh\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">means:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Give execute permission to user, group, and others.\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Another example:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>chmod 777 file.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">means:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Owner  = read + write + execute\nGroup  = read + write + execute\nOthers = read + write + execute\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">So <code>777<\/code> is very broad. It gives <strong>everyone<\/strong> full access.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>r = 4\nw = 2\nx = 1\n\n7 = 4 + 2 + 1 = rwx\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">So:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>777 = rwxrwxrwx\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">This is usually <strong>not safe<\/strong>, especially for shared systems.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">2. ACL permissions<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">ACL means <strong>Access Control List<\/strong>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">ACL lets you give permission to <strong>specific extra users or groups<\/strong>, without changing the main owner\/group\/others permissions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Example:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>setfacl -m u:john:rwx project.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">This gives user <code>john<\/code> read, write, and execute permission on <code>project.txt<\/code>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Check ACL:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>getfacl project.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Remove John\u2019s ACL:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>setfacl -x u:john project.txt\n<\/code><\/pre>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Main difference<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Feature<\/th><th>UGO \/ chmod<\/th><th>ACL \/ setfacl<\/th><\/tr><\/thead><tbody><tr><td>Basic permission system<\/td><td>Yes<\/td><td>Extended permission system<\/td><\/tr><tr><td>Controls owner, group, others<\/td><td>Yes<\/td><td>Yes, but with extra rules<\/td><\/tr><tr><td>Give permission to one specific extra user<\/td><td>Limited<\/td><td>Yes<\/td><\/tr><tr><td>Good for simple permissions<\/td><td>Yes<\/td><td>Yes<\/td><\/tr><tr><td>Good for complex\/shared access<\/td><td>Not ideal<\/td><td>Better<\/td><\/tr><tr><td>Example<\/td><td><code>chmod 755 file<\/code><\/td><td><code>setfacl -m u:john:rwx file<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Example situation<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Suppose you have this file:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>ls -l report.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Output:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>-rw------- 1 sayed sayed report.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Only <code>sayed<\/code> can read and write.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Now you want only <code>john<\/code> to also read it.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Bad approach:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>chmod 777 report.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">This gives <strong>everyone<\/strong> full access.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Better approach:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>setfacl -m u:john:r report.txt\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">This gives <strong>only John<\/strong> read permission.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">Simple summary<\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>chmod \/ UGO = basic permissions for owner, group, and everyone else.\nACL = extra detailed permissions for specific users or groups.\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Use <code>chmod 777<\/code> only in rare testing situations. For real systems, ACL is safer when you want to give access to one specific user or group.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">REF: AI Tools\/ChatGPT<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux has two main permission layers: 1. Traditional UGO permissions UGO means: Example: means: Another example: means: So 777 is very broad. It gives everyone full access. So: This is usually not safe, especially for shared systems. 2. ACL permissions ACL means Access Control List. ACL lets you give permission to specific extra users or &hellip; <\/p>\n<p><a class=\"more-link btn\" href=\"http:\/\/bangla.sitestree.com\/?p=78680\">Continue reading<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1976],"tags":[],"class_list":["post-78680","post","type-post","status-publish","format-standard","hentry","category-anything-linux","item-wrap"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":71266,"url":"http:\/\/bangla.sitestree.com\/?p=71266","url_meta":{"origin":78680,"position":0},"title":"Difference: Auto-Regressive and Auto Correlation.","author":"Sayed","date":"September 27, 2021","format":false,"excerpt":"If you can, answer the question below: Write your answer in the comment box. 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