作业一：
1) 新建用户natasha，uid为1000，gid为555，备注信息为“master”
useradd natasha -u 1000 -g 555 -c "master"
2) 修改natasha用户的家目录为/Natasha
usermod -d /Natasha natasha
su - natasha
-bash-4.1$ pwd
/home/Natasha
-bash-4.1$
3) 查看用户信息配置文件的最后一行
tail -1 /etc/passwd
4) 为natasha用户设置密码“123”
echo '123'|passwd --stdin natasha
5) 查看用户密码配置文件的最后一行
tail -1 /etc/shadow
6) 将natasha用户账户锁定
passwd -l natasha
usermod -s /sbin/nologin natasha
7) 将natasha用户账户解锁
passwd -u natasha
usermod -s /bin/bash natasha
8) 新建组police，gid为999
groupadd police -g 999
9) 查看组配置文件的最后一行
tail -1 /etc/group
10) 将natasha用户加入police组
usermod -a -G police natasha
11) 修改police组的组名为jingcha
groupmod -n jingcha police
12) 删除natasha用户，连家目录和邮箱一起删除
userdel natasha -r
13) 删除jingcha组
groupdel jingcha
作业二：
1) 在用户的主目录下创建目录test，进入test创建空文件file1
cd /home/ && mkdir test && touch test/file1
2) 以长格式形式显示文件信息，注意文件的权限和所属用户和组
ls -l test/
[natasha@iZ25j36rr97Z ~]$ ls -l test/
total 0
-rw-rw-r-- 1 natasha natasha 0 May 24 17:00 file1
3) 为文件file1设置权限，使其他用户可以对此文件进行写操作。
chmod o=w test/file1
4) 查看设置结果，
-bash-4.1$ ll test/
-rw-rw--w- 1 natasha natasha 0 May 24 17:14 file1a
5) 取消同组用户对文件file1的读取权限，并查看设置结果。
chmod g-r file1
-rw--w--w- 1 natasha natasha 0 May 24 16:54 file1
6) 用数字表示法为文件file设置权限，所有者可读、可写、可执行，所属组用户和其他用户只具有读和执行的权限。设置完成后查看设置结果。
chmod 755 file1
[natasha@iZ25j36rr97Z ~]$ ll test/file1
-rwxr-xr-x 1 natasha natasha 0 May 24 16:54 test/file1
7) 用数字形式更改文件file1的权限，使所有者只能读取此文件。其他任何用户都没有权限。查看设置结果。
chmod 500 test/
chmod 400 file1
8) 回到上层目录，查看test的权限
cd .. && ll test
dr-x------ 2 natasha natasha 4096 May 24 15:13 test
9) 为其他用户添加对此目录的写权限
chmod o+wx test/ -R
作业三：
以操作文件的方式，新建一个用户alex
echo 'alex:x:1004:1004:master:/home/alex:/bin/bash' >>/etc/passwd
echo 'alex:!!:17310:0:99999:7:::' >> /etc/shadow
echo 'alex:x:666:' >>group
echo 'alex:!::' >> /etc/gshadow
touch /var/spool/mail/alex
uid=1004(alex) gid=1004 groups=1004
作业四：
1) 新建目录/test/dir，属主为tom，数组为group1，/test目录的权限为777
mkdir /test/dir -p && chown tom.group1 /test/dir -R
chmod 777 /test
2) 新建用户jack，切换到jack用户下，验证jack用户对dir目录的rwx权限（开启另外一个终端，依次修改dir目录的others权限）
useradd jack
su - jack
3）将jack加入group1组，验证jack用户对dir目录的rwx权限（开启另外一个终端，依次修改dir目录的group权限）
usermod -a -G group1 jack
[root@iZ25j36rr97Z test]# chmod g=- dir/
[root@iZ25j36rr97Z test]# ll
total 4
drwx---r-x 2 tom group1 4096 May 25 19:22 dir
[jack@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[jack@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod g=r dir
[root@iZ25j36rr97Z test]# ll
total 4
drwxr--r-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[jack@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod g=w dir
[root@iZ25j36rr97Z test]# ll
total 4
drwx-w-r-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[jack@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod g=x dir
[root@iZ25j36rr97Z test]# ll
total 4
drwx--xr-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
[jack@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z test]# chmod g=rw dir
[root@iZ25j36rr97Z test]# ll
total 4
drwxrw-r-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[jack@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod g=rx dir
[root@iZ25j36rr97Z test]# ll
total 4
drwxr-xr-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
[jack@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[jack@iZ25j36rr97Z test]$ cd dir
[jack@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z test]# chmod g=wx dir
[root@iZ25j36rr97Z test]# ll
total 4
drwx-wxr-x 2 tom group1 4096 May 25 19:22 dir
[root@iZ25j36rr97Z test]#
[jack@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[jack@iZ25j36rr97Z test]$ touch dir/1
[jack@iZ25j36rr97Z test]$ cd dir
[jack@iZ25j36rr97Z dir]$
4）切换到tom用户，验证tom用户对dir目录的rwx权限（开启另外一个终端，依次修改dir目录的user权限）
[root@iZ25j36rr97Z test]# chmod u=- dir
[root@iZ25j36rr97Z test]# ll
total 4
d----wxr-x 2 tom group1 4096 May 25 19:40 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ ll
total 4
drwx-wxr-x 2 tom group1 4096 May 25 19:40 dir
[tom@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[tom@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[tom@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod u=r dir
[root@iZ25j36rr97Z test]# ll
total 4
dr---wxr-x 2 tom group1 4096 May 25 19:40 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ ls dir
ls: cannot access dir/1: Permission denied
1
[tom@iZ25j36rr97Z test]$ touch dir/2
touch: cannot touch `dir/2': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[tom@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod u=w dir
[root@iZ25j36rr97Z test]# ll
total 4
d-w--wxr-x 2 tom group1 4096 May 25 19:40 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ touch dir/2
touch: cannot touch `dir/2': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[tom@iZ25j36rr97Z test]$ ll
total 4
d-w--wxr-x 2 tom group1 4096 May 25 19:40 dir
[tom@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod u=x dir
[root@iZ25j36rr97Z test]# ll
total 4
d--x-wxr-x 2 tom group1 4096 May 25 19:40 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[tom@iZ25j36rr97Z test]$ touch dir/1
touch: cannot touch `dir/1': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
[tom@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z test]# chmod u=rw dir
[root@iZ25j36rr97Z test]# ll
total 4
drw--wxr-x 2 tom group1 4096 May 25 19:40 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ ls dir
ls: cannot access dir/1: Permission denied
1
[tom@iZ25j36rr97Z test]$ touch dir/3
touch: cannot touch `dir/3': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
-bash: cd: dir: Permission denied
[tom@iZ25j36rr97Z test]$ ll
total 4
drw--wxr-x 2 tom group1 4096 May 25 19:40 dir
[tom@iZ25j36rr97Z test]$
[root@iZ25j36rr97Z test]# chmod u=rx dir
[root@iZ25j36rr97Z test]# ll
total 4
dr-x-wxr-x 2 tom group1 4096 May 25 19:40 dir
[tom@iZ25j36rr97Z test]$ ll
total 4
dr-x-wxr-x 2 tom group1 4096 May 25 19:40 dir
[tom@iZ25j36rr97Z test]$ ls dir
1
[tom@iZ25j36rr97Z test]$ touch dir/3
touch: cannot touch `dir/3': Permission denied
[tom@iZ25j36rr97Z test]$ cd dir
[tom@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z test]# chmod u=xw dir
[root@iZ25j36rr97Z test]# ll
total 4
d-wx-wxr-x 2 tom group1 4096 May 25 19:49 dir
[root@iZ25j36rr97Z test]#
[tom@iZ25j36rr97Z test]$ ls dir
ls: cannot open directory dir: Permission denied
[tom@iZ25j36rr97Z test]$ touch dir/3
[tom@iZ25j36rr97Z test]$ cd dir
[tom@iZ25j36rr97Z dir]$
5）在dir目录内新建文件tom.txt,属主为tom，属组为group1，/test目录的权限为777
chown tom.group1 tom.txt
chmod 777 /test
6）新建用户rose，切换到rose用户下，验证rose用户对tom.txt的rwx权限（开启另外一个终端，依次修改tom.txt的others权限来配合验证过程）
[rose@iZ25j36rr97Z test]$ ll dir
total 0
-rw-r--r-- 1 tom group1 0 May 24 17:58 tom.txt
[rose@iZ25j36rr97Z test]$ echo '1' >dir/tom.txt
-bash: dir/tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
[rose@iZ25j36rr97Z dir]$ sh tom.txt
5
[root@iZ25j36rr97Z dir]# chmod o=- tom.txt
[rose@iZ25j36rr97Z dir]$ ll
total 0
-rw-r----- 1 tom group1 0 May 24 17:58 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ echo '11' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ sh tom.txt
sh: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod o=w tom.txt
[rose@iZ25j36rr97Z dir]$ ll tom.txt
-rw-r---w- 1 tom group1 3 May 24 18:02 tom.txt
[rose@iZ25j36rr97Z dir]$ echo '11' >tom.txt
[rose@iZ25j36rr97Z dir]$ sh tom.txt
sh: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod o=x tom.txt
[rose@iZ25j36rr97Z dir]$ ll
total 4
-rw-r----x 1 tom group1 3 May 24 18:02 tom.txt
[rose@iZ25j36rr97Z dir]$ echo '11' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ sh tom.txt
sh: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod o=rw tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
-rw-r--rw- 1 tom group1 3 May 24 18:02 tom.txt
[rose@iZ25j36rr97Z dir]$ echo '3' >tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
echo '3'
[rose@iZ25j36rr97Z dir]$ sh tom.txt
3
[root@iZ25j36rr97Z dir]# chmod o=rx tom.txt
[rose@iZ25j36rr97Z dir]$ ll
total 4
-rw-r--r-x 1 tom group1 31 May 24 18:35 tom.txt
[rose@iZ25j36rr97Z dir]$./tom.txt
3
'3'
'3'
[rose@iZ25j36rr97Z dir]$ cat tom.txt
echo '3'
echo \'3\'
echo \'3\'
[rose@iZ25j36rr97Z dir]$ echo "echo \'4\'" >>tom.txt
-bash: tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod o=wx tom.txt
[rose@iZ25j36rr97Z dir]$ ll
total 4
-rw-r---wx 1 tom group1 20 May 24 18:33 tom.txt
[rose@iZ25j36rr97Z dir]$ echo "echo \'3\'" >>tom.txt
[rose@iZ25j36rr97Z dir]$ ./tom.txt
bash: ./tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod o=rwx tom.txt
[rose@iZ25j36rr97Z dir]$ ll
total 4
-rw-r---wx 1 tom group1 20 May 24 18:33 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
echo '3'
echo \'3\'
[rose@iZ25j36rr97Z dir]$ ./tom.txt
3
'3'
[rose@iZ25j36rr97Z dir]$ echo "echo \'3\'" >>tom.txt
7）将rose加入group1组，在rose用户下，验证rose用户对tom.txt的rwx权限（开启另外一个终端，依次修改tom.txt的group1权限来配合验证过程）
usermod -a -G group1 rose
[rose@iZ25j36rr97Z dir]$ ll
total 0
-rw-r--r-- 1 tom group1 0 May 24 18:48 tom.txt
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ cat tom.txt
[rose@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod g=- tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ ll tom.txt
-rw----r-- 1 tom group1 0 May 24 18:48 tom.txt
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod g=r tom.txt
[rose@iZ25j36rr97Z dir]$ ll tom.txt
-rw-r--r-- 1 tom group1 0 May 24 18:48 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod g=w tom.txt
[rose@iZ25j36rr97Z dir]$ ll tom.txt
-rw--w-r-- 1 tom group1 0 May 24 18:48 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
[root@iZ25j36rr97Z dir]# chmod g=x tom.txt
[rose@iZ25j36rr97Z dir]$ ll tom.txt
-rw---xr-- 1 tom group1 2 May 24 18:52 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$./tom.txt
bash: ./tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod g=rw tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
-rw-rw-r-- 1 tom group1 2 May 24 18:52 tom.txt
[root@iZ25j36rr97Z dir]#
[rose@iZ25j36rr97Z dir]$ cat tom.txt
1
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
[rose@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod g=rx tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
-rw-r-xr-- 1 tom group1 2 May 24 18:59 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
echo '2'
[rose@iZ25j36rr97Z dir]$ echo 'ls ' >tom.txt
-bash: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ ./tom.txt
2
[root@iZ25j36rr97Z dir]# chmod g=wx tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
-rw--wxr-- 1 tom group1 9 May 24 19:02 tom.txt
[rose@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ ./tom.txt
bash: ./tom.txt: Permission denied
[rose@iZ25j36rr97Z dir]$ echo '1' >tom.txt
[root@iZ25j36rr97Z dir]# chmod g=rwx tom.txt
[root@iZ25j36rr97Z dir]# ll tom.txt
-rw-rwxr-- 1 tom group1 13 May 24 19:07 tom.txt
[root@iZ25j36rr97Z dir]#
[rose@iZ25j36rr97Z dir]$ ./tom.txt
222
[rose@iZ25j36rr97Z dir]$ cat tom.txt
echo '222'
[rose@iZ25j36rr97Z dir]$ echo '1' >>tom.txt
8）切换到tom用户，验证tom用户对tom.txt的rwx权限（开启另外一个终端，依次修改tom.txt的user权限来配合验证过程）
[root@iZ25j36rr97Z dir]# chmod u=- tom.txt
[tom@iZ25j36rr97Z dir]$ ll
total 0
----rw-r-- 1 tom group1 0 May 24 19:14 tom.txt
[tom@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '11' >tom.txt
-bash: tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$
[root@iZ25j36rr97Z dir]# chmod u=r tom.txt
[tom@iZ25j36rr97Z dir]$ cat tom.txt
[tom@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '1' > tom.txt
-bash: tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod u=w tom.txt
[root@iZ25j36rr97Z dir]# ll
total 0
--w-rw-r-- 1 tom group1 0 May 24 19:14 tom.txt
[tom@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '1' > tom.txt
[tom@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# ll
total 4
---xrw-r-- 1 tom group1 2 May 24 19:18 tom.txt
[tom@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ ./tom.txt
bash: ./tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '1' > tom.txt
-bash: tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod u=rw tom.txt
[root@iZ25j36rr97Z dir]# ll
total 0
-rw-rw-r-- 1 tom group1 0 May 24 19:21 tom.txt
[root@iZ25j36rr97Z dir]#
[tom@iZ25j36rr97Z dir]$ cat tom.txt
[tom@iZ25j36rr97Z dir]$ ./tom.txt
-bash: ./tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '1' > tom.txt
[root@iZ25j36rr97Z dir]# chmod u=rx tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
-r-xrw-r-- 1 tom group1 2 May 24 19:23 tom.txt
[root@iZ25j36rr97Z dir]#
[tom@iZ25j36rr97Z dir]$ cat tom.txt
echo '1'
[tom@iZ25j36rr97Z dir]$ ./tom.txt
1
[tom@iZ25j36rr97Z dir]$ echo '1' >> tom.txt
-bash: tom.txt: Permission denied
[root@iZ25j36rr97Z dir]# chmod u=wx tom.txt
[root@iZ25j36rr97Z dir]# ll
total 4
--wxrw-r-- 1 tom group1 11 May 24 19:35 tom.txt
[tom@iZ25j36rr97Z dir]$ cat tom.txt
cat: tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ ./tom.txt
bash: ./tom.txt: Permission denied
[tom@iZ25j36rr97Z dir]$ echo '1' >> tom.txt
[tom@iZ25j36rr97Z dir]$
