How Linux determines how the specified user's permissions on the specified directory are specifically described

Script Name: power.sh

Script content:

The code is as follows:

#!/bin/sh

Username3=$1

Dir_name2=$2

# Get existing Directory

File_path= $dir _name2

While True

Todo

If [D-$file _path];then

Break

Fi

file_path=${file_path%/*}

Done

dir_name2= $file _path

# Judge whether the user exists

grep "^ $username 3:"/etc/passwd >/dev/null

If [$?-ne 0];then

echo "This user" $username 3 "does not exist."

Exit 4

Fi

#echo "Username: $username 3"

group4= ' grep ' ^ $username 3: "/etc/passwd |awk-f: {' Print $ '}|xargs-i grep {}/etc/group|cut-d": "-f1"

#echo "Group: $group 4"

Su-l $username 3-c "Test-r $dir _name2"

Is_read=$?

Su-l $username 3-c "Test-x $dir _name2"

Is_exe=$?

Su-l $username 3-c "test-w $dir _name2"

Is_write=$?

$is _read_str

$is _exe_str

$is _write_str

If [$is _read-eq 0];then

Is_read_str= "R"

Else

Is_read_str= "-"

Fi

If [$is _exe-eq 0];then

Is_exe_str= "X"

Else

Is_exe_str= "-"

Fi

If [$is _write-eq 0];then

Is_write_str= "W"

Else

Is_write_str= "-"

Fi

echo "${is_read_str}${is_write_str}${is_exe_str}"

-------------------------------------------

Note: This script must be executed as root.

Script power.sh requires two parameters, the first represents the specified user, and the second represents the specified directory

Test:

[Root@ppc40 study]# sh power.sh whuanga4/tmp/abc/dd

This user "Whuanga4" does not exist.

[Root@ppc40 study]# sh power.sh whuang4/tmp/abc/dd

rw-

(Note: Indicates that the user Whuang4 has read and write access to the directory/tmp/abc/dd and does not have execute permissions).