Chmod 备忘清单

这份快速参考备忘单提供了文件权限的简要概述,以及 chmod 命令的操作

入门

语法

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$ chmod [options] <permissions> <file> 

示例

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$ chmod 755 foo.txt
$ chmod +x quickref.py
$ chmod u-x quickref.py
$ chmod u=rwx,g=rx,o= quickref.sh

递归更改文件和目录

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$ chmod -R 755 my_directory

chmod 命令代表“更改模式”

Chmod 生成器

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<div>
权限:<input type="text" id="num" placeholder="777" maxlength="3" style="padding: 0.3rem 0.3rem;" /> <input type="text" id="let" placeholder="rwxrwxrwx" maxlength="9" style="padding: 0.3rem 0.3rem;" />
</div>

  User Group Other
(Read)
(Write)
执行 (Execute)

Chmod 生成器允许您以数字和符号的形式快速、直观地生成权限。

通用权限

命令 s 含义
400 r——– 仅所有者可读
500 r-x—— 避免改变
600 rw——- 可由用户更改
644 rw-r–r– 由用户读取和更改
660 rw-rw—- 可由用户和组更改
700 rwx—— 只有用户具有完全访问权限
755 rwxr-xr-x 只能由用户更改
775 rwxrwxr-x 群组共享模式
777 rwxrwxrwx 每个人都可以做任何事

解释

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$ ls -l
-rw-r--r-- 1 root root 3 Jun 29 15:35 a.log
drwxr-xr-x 2 root root 2 Jun 30 18:06 dir

dir 的权限分析

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d  rwx  r-x  r-x
┬ ─┬─ ─┬─ ─┬─
┆ ┆ ┆ ┆
┆ ┆ ┆ ╰─ 4. Other|5 (4+0+1)
┆ ┆ ╰────── 3. Group|5 (4+0+1)
┆ ╰─────────── 2. User |7 (4+2+1)
╰─────────────── 1. File Type | directory

权限模式

权限 描述 八进制 十进制
--- 没有权限 000 0 (0+0+0)
--x 执行 001 1 (0+0+1)
-w- 010 2 (0+2+0)
-wx 执行和写入 011 3 (0+2+1)
r-- 100 4 (4+0+0)
r-x 读取和执行 101 5 (4+0+1)
rw- 读和写 110 6 (4+2+0)
rwx 读取、写入和执行 111 7 (4+2+1)

Objects

谁(缩写) 含义
u 用户
g
o 其它
a 全部,和 ugo 一样

权限

缩写 权限
r 4
w 2
x 执行 1
- 没有权限 0

文件类型

缩写 文件类型
d 目录
- 常规文件
l 符号链接

Chmod 示例

操作符

Symbol Description
+ 添加
- 删除
= 设置

chmod 600

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$ chmod 600 example.txt
$ chmod u=rw,g=,o= example.txt
$ chmod a+rwx,u-x,g-rwx,o-rwx example.txt

chmod 664

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$ chmod 664 example.txt
$ chmod u=rw,g=rw,o=r example.txt
$ chmod a+rwx,u-x,g-x,o-wx example.txt

chmod 777

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$ chmod 777 example.txt
$ chmod u=rwx,g=rwx,o=rwx example.txt
$ chmod a=rwx example.txt

符号模式

拒绝所有人的执行权限。

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$ chmod a-x chmodExampleFile.txt

向所有人授予读取权限。

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$ chmod a+r chmodExampleFile.txt

使文件可由组和其他人读写。

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$ chmod go+rw chmodExampleFile.txt

使用户/所有者可执行 shell。

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$ chmod u+x chmodExampleScript.sh

允许每个人读取、写入和执行文件并打开设置的 group-ID。

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$ chmod =rwx,g+s chmodExampleScript.sh

删除权限

要删除赋予文件的读写权限,请使用以下语法:

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$ chmod o-rw example.txt

对于我们的文件 example.txt,我们可以通过运行以下命令使用 chmod for group 删除读写权限:

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$ chmod  g-rx example.txt

要从组中删除 chmod 读写权限,同时向 public/others 添加读写权限,我们可以使用以下命令:

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$ chmod g-rx, o+rx example.txt

但是,如果你想删除组和其他人的所有权限,你可以使用 go= 来代替:

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$ chmod go= example.txt

可执行文件

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$ chmod +x ~/example.py
$ chmod u+x ~/example.py
$ chmod a+x ~/example.py

chmod 754

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$ chmod 754 foo.sh
$ chmod u=rwx,g=rx,o=r foo.sh

Chmod 实践

SSH 权限

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$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/authorized_keys
$ chmod 600 ~/.ssh/id_rsa
$ chmod 600 ~/.ssh/id_rsa.pub
$ chmod 400 /path/to/access_key.pem

网络权限

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$ chmod -R 644 /var/www/html/
$ chmod 644 .htaccess
$ chmod 644 robots.txt
$ chmod 755 /var/www/uploads/
$ find /var/www/html -type d -exec chmod 755 {} \;

批量更改

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$ chmod -R 644 /your_path
$ find /path -type d -exec chmod 755 {} \;
$ find /path -type f -exec chmod 644 {} \;

请参阅:命令替换

另见

以下是 Chmod 生成器 JS 代码(代码用于网站请忽略不要删除)

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<!-- Chmod 生成器 JS 代码 -->
<script type="text/javascript">
const reg_num = /^[0-7]{3}$/; // 一些正则表达式来检查 num 输入
const reg_let = /^([r\-]{1}[w\-]{1}[x\-]{1}){3}$/; // 一些正则表达式来检查文本输入
function checkBoxHandle() {
change_occured(true, false, false);
// get rid of bad input classes
document.getElementById('num').classList.remove('bad-input');
document.getElementById('let').classList.remove('bad-input');
}
window.addEventListener("DOMContentLoaded", function () {
// loop over all the check boxes
for (let i = 1; i < 10; i++) {
let checkBox = document.getElementById(`${i}`);
checkBox.addEventListener('change', function () {
change_occured(true, false, false);

// get rid of bad input classes
document.getElementById('num').classList.remove('bad-input');

document.getElementById('let').classList.remove('bad-input');
});
}
// the octal input
let num_input = document.getElementById('num');
let num_fn = function () {
// check for bad input
if (!reg_num.test(this.value)) {
this.classList.add('bad-input');
} else {
this.classList.remove('bad-input');
change_occured(false, true, false);
}
};
num_input.addEventListener('change', num_fn);
num_input.addEventListener('keyup', num_fn);
// the let input
let let_input = document.getElementById('let');
let let_fn = function () {
// check for bad input
if (!reg_let.test(this.value)) {
this.classList.add('bad-input');
} else {
this.classList.remove('bad-input');
change_occured(false, false, true);
}
};
let_input.addEventListener('change',let_fn);
let_input.addEventListener('keyup',let_fn);
});
/* SETUP
r-4-1 r-4-4 r-4-7
w-2-2 w-2-5 w-2-8
x-1-3 x-1-6 x-1-9
*/
// define a function that runs when a change occures
function change_occured(caller_was_check, caller_was_num, caller_was_let) {
let num1 = 0, num2 = 0, num3 = 0; // these are the three numbers for the octal
let perm_string = ''; // holds the permision string ex. rw-x--r--
if (caller_was_check) {
// loop over all the check boxes and get the permisions
for (let i = 1; i < 10; i++) {
let checkBox = document.getElementById(`${i}`);
if (checkBox.checked) { // if checked
let current_perm = check_to_octal_and_text(i);
perm_string += `${current_perm.perm_let}`;
if (i <= 3) {
num1 += current_perm.perm_num;
} else if (i <= 6) {
num2 += current_perm.perm_num;
} else {
num3 += current_perm.perm_num;
}
} else { // if not checked
perm_string += '-';
}
}
// set the permision input text
document.getElementById('let').value = perm_string;
document.getElementById('num').value = `${num1}${num2}${num3}`;
} else if (caller_was_num) {
// get the individual numbers
let num_input_val = document.getElementById('num').value;
num1 = num_input_val.substring(0, 1);
num2 = num_input_val.substring(1, 2);
num3 = num_input_val.substring(2, 3);
// set the checkboxes and get the perm string
perm_string += octal_to_check_and_txt(num1, 0); //Owner
perm_string += octal_to_check_and_txt(num2, 1); //Owner
perm_string += octal_to_check_and_txt(num3, 2); //Owner
// set the permision input text
document.getElementById('let').value = perm_string;
} else if (caller_was_let) {
// get the text input
let perm_text = document.getElementById('let').value;
num1 = text_to_check_and_octal(perm_text.substring(0, 3), 0)
num2 = text_to_check_and_octal(perm_text.substring(3, 6), 3)
num3 = text_to_check_and_octal(perm_text.substring(6, 9), 6)
// set the octal value
document.getElementById('num').value = `${num1}${num2}${num3}`;
}
}
// define a function to converts the checkbox # to the respective permissions
// returns perm_num, perm_let
function check_to_octal_and_text(check_num) {
let perm_num = 0;
let perm_let = '-';
switch (check_num) {
case 1:
case 4:
case 7:
perm_num = 4;
perm_let = 'r';
break;
case 2:
case 5:
case 8:
perm_num = 2;
perm_let = 'w';
break;
case 3:
case 6:
case 9:
perm_num = 1;
perm_let = 'x';
break;
default:
perm_num = 0;
perm_let = '-';
}
// return values
return {
perm_num,
perm_let
};
}
/**
Takes a number 1-7 and which class it is in:
0 = owner
1 = Group
2 = Public
Returns: perm text (ex. "rwx") and sets the appropriate checkboxes
*/
function octal_to_check_and_txt(octal_num, class_num) {
let perm_text = '';
let offset = class_num * 3;
switch (octal_num) {
case '1':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = '--x';
break;
case '2':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = '-w-';
break;
case '3':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = '-wx';
break;
case '4':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = 'r--';
break;
case '5':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = 'r-x';
break;
case '6':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = 'rw-';
break;
case '7':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = 'rwx';
break;
default:
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = '---';
}
return perm_text;
}
/**
Takes 3 letters (r, w, x, - ex. 'rw-') and an offset (0,3,6)
Returns the octal num and sets the appropriate checkboxes
*/
function text_to_check_and_octal(letters, offset) {
let perm_num = 0; // the octal number to return
// add up the oct num and set the check boxes
for (let i = 0; i < 3; i++) {
current_let = letters.substring(i, i + 1);
if (current_let == 'r') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 4;
} else if (current_let == 'w') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 2;
} else if (current_let == 'x') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 1;
} else {
document.getElementById(`${i + 1 + offset}`).checked = false;
}
}
return perm_num;
}
</script>