CS-Notes/notes/Linux.md

<!-- GFM-TOC -->
* [???<3F><>??????????](#???<3F><>??????????)
    * [????](#????)
    * [???](#???)
    * [??????](#??????)
    * [?????](#?????)
    * [PATH](#path)
    * [???<3F><>??](#???<3F><>??)
    * [sudo](#sudo)
    * [GNU](#gnu)
    * [????????](#????????)
    * [???????<3F>ѷ<EFBFBD>](#???????<3F>ѷ<EFBFBD>)
* [????](#????)
    * [??????????](#??????????)
    * [??????](#??????)
        * [1. MBR](#1-mbr)
        * [2. GPT](#2-gpt)
    * [??????????](#??????????)
        * [1. BIOS](#1-bios)
        * [2. UEFI](#2-uefi)
    * [????](#????)
* [??????????????](#??????????????)
    * [?????????](#?????????)
    * [?????????????????](#?????????????????)
        * [1. ?????????????](#1-?????????????)
        * [2. ???????????](#2-???????????)
        * [3. ??????](#3-??????)
    * [???????](#???????)
    * [?????????](#?????????)
    * [??????](#??????)
* [???????](#???????)
    * [??????](#??????)
    * [????????????????](#????????????????)
        * [1. ls](#1-ls)
        * [2. cp](#2-cp)
        * [3. rm](#3-rm)
        * [4. mv](#4-mv)
    * [??????????](#??????????)
        * [1. cat](#1-cat)
        * [2. tac](#2-tac)
        * [3. more](#3-more)
        * [4. less](#4-less)
        * [5. head](#5-head)
        * [6. tail](#6-tail)
        * [7. od](#7-od)
        * [8. touch](#8-touch)
    * [????????????](#????????????)
        * [1. which](#1-which)
        * [2. whereis](#2-whereis)
        * [3. locate](#3-locate)
        * [4. find](#4-find)
            * [4.1 ??????<3F><>?????](#41-??????<3F><>?????)
            * [4.2 ???????????????????<3F><>?????](#42-???????????????????<3F><>?????)
            * [4.3 ??????????????<3F><>?????](#43-??????????????<3F><>?????)
* [???????????](#???????????)
    * [??????????](#??????????)
    * [inode](#inode)
    * [???? inode ?? block](#????-inode-??-block)
    * [????????????????](#????????????????)
        * [1. ???????](#1-???????)
        * [2. ????????](#2-????????)
* [???????](#???????)
    * [???](#???)
        * [1. gzip](#1-gzip)
        * [2. bzip2](#2-bzip2)
        * [3. xz](#3-xz)
    * [???](#???)
* [BASH](#bash)
    * [Bash????](#bash????)
    * [????????](#????????)
    * [??????????](#??????????)
    * [???????????](#???????????)
    * [???????](#???????)
        * [1. ??????cut](#1-??????cut)
        * [2. ????????sort??uniq](#2-????????sort??uniq)
        * [3. ???????????tee](#3-???????????tee)
        * [4. ?????????tr??col??expand??join??paste](#4-?????????tr??col??expand??join??paste)
        * [5. ???????split](#5-???????split)
* [??????????????????????](#??????????????????????)
    * [grep](#grep)
    * [printf](#printf)
    * [awk](#awk)
* [vim ??????](#vim-??????)
* [?<3F><>?????](#?<3F><>?????)
<!-- GFM-TOC -->

# ???<3F><>??????????

## ????

**1. --help**

????????<3F><>??????????

**2. man**

man ?? manual ????<3F><>???????????????????????

????? man date ????? DATE(1) ????????<3F><>??????????????????????????????????????

| ???? | ???? |
| -- | -- |
| 1 | ????? shell ?????<3F><>????????????????????? |
| 5 | ??????? |
| 8 | ????????????????????? |

**3. info**

info ?? man ????????? info ???????????????<3F><>?????????????????

## ???

**1. ???????<3F><>????? sync**

?????????????????<3F><>????<3F><>??????<3F><>?????????????????????????????????????????? sync ?????????

**2. shutdown**

```html
# /sbin/shutdown [-krhc] [???] [??????]
-k ?? ???????????????????????????????????
-r ?? ???????????????????????
-h ?? ??????????????????????
-c ?? ??????????<3F><>? shutdown ???????
```

**3. ??????????**

reboot??halt??poweroff??

## ??????

ps ??<3F><>

????? theadx ??????????

```html
ps aux | grep threadx
```

## ?????

netstat ??<3F><>

???????? 80 ???????

```html
netstat -anp | grep 80
```

## PATH

????????????? PATH ????????????????<3F><>????<3F><>??????? : ?????

```html
/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/dmtsai/.local/bin:/home/dmtsai/bin
```

## ???<3F><>??

0???????
1????????????????????root????
2??????????????????
3??????????????????????????????????????????
4????????<3F><>???
5???????????? X-windows ??????????????<3F><>
6????????????????????

## sudo

??? sudo ????????????? root ????<3F><>????<3F><>????????? /etc/sudoers ?<3F><>?????????<3F><>

## GNU

GNU ????????????<3F><>?????????????????????????????????????? GNU???????????????? GPL ????????????? GPL ???? GNU ??<3F><>??????<3F><>?<3F><>???????????????

- ???<3F><>???????<3F><>??????????
- ???????????
- ?????????????????????????<3F><>?

## ????????

RPM ?? DPKG ???????????????????????RPM ???? Redhat Package Manager???????? Red Hat ????????????? GNU ???????????????????? Linux ?? (RHEL) ?????????????? RPM ???<3F><>?????????? Debian ?????? (UBUNTU) ?? DEB ???????????? DPKG?????? Debian Package??????????? RPM ?????

YUM ???? RPM ?????????????????????????????????????????????????? RPM ???????????????????????????????????????????????????????????????????????????????????????????????????YUM ???????????????????????????????????

## ???????<3F>ѷ<EFBFBD>

Linux ???<3F><>??????????? Linux ????????????????

**???? DPKG**

??????<3F><>?

- Ubuntu

???????<3F><>?

- Debian

**???? RPM**

??????<3F><>?

- Red Hat

???????<3F><>?

- Fedora
- CentOS

# ????

## ??????????

Linux ????????????????????????

????????????????

- SCSI/SATA/USB ?????/dev/sd[a-p]
- IDE ?????/dev/hd[a-d]

??????????????????????????????????<3F><>??????????????????<3F><>??????

## ??????

?????????????????????????????????? MBR ???????????????????????? GPT ??????

### 1. MBR

MBR ?<3F><>??????????????????????<3F><>?????????????Master boot record, MBR??????????partition table???????? MBR ? 446 bytes??partition table ? 64 bytes??

????????? 64 bytes????????<3F><> 4 ?????????? 4 ???????????????Primary?????????????Extended?????????????????????????????????????????????????????????????????????????????????????????????<3F><>????????????????

Linux ???????????????????????????????????????????+???????? /dev/sda1????????????????? 5 ?????

### 2. GPT

?????????<3F><>??????????<3F><>?????? 512bytes ?????????? 4k??GPT ?????????<3F><>?????????????????????????????Logical Block Address, LBA????

GPT ?? 1 ?????????? MBR?????????? 33 ????????????????????????? 33 ????????????????????<3F><>????

GPT ????????????????????????????????? 128 ????????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/a5c25452-6fa5-49e7-9322-823077442775.jpg)

## ??????????

### 1. BIOS

BIOS ????????????????<3F><>??????????????????????????????????????????????????? MBR???? MBR ??????<3F><>?????????????????????????????????????????????

MBR ?<3F><>????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? MBR ?<3F><>???????????????????????????????????????????????????????????????????????????????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/f900f266-a323-42b2-bc43-218fdb8811a8.jpg)

???????????????????? Windows ???? Linux???????? Windows ?????? MBR???? Linux ???????????????????? MBR ???????????????????????????????????????????????????

### 2. UEFI

UEFI ????? BIOS ???????????<3F><>?????????

## ????

?????????????????????????????????????????????????????????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/249f3bb1-feee-4805-a259-a72699d638ca.jpg)

# ??????????????

## ?????????

?????????????????????????????????????????????<3F><>???????????

??? ls ????????????????????????????????? drwxr-xr-x. 3 root root 17 May 6 00:14 .config????????????????????

- drwxr-xr-x?????????????????? 1 <20><>??????????<3F><>??? 9 <20><>?????????<3F><>?
- 3??????????
- root???????????
- root????????<3F><>
- 17???????<3F><>??
- May 6 00:14???????????????
- .config?????????

???????????????<3F><>???<3F><>?

- d??????
- -???????
- l???????????

9 <20><>????????????<3F><>?? 3 ?????<3F><>?? 3 ?<3F><>??????????????????????????????????????????????????<3F><>? 3 <20><>???? r??w??x ??????????????<3F><>??????<3F><>?

## ?????????????????

### 1. ?????????????

```html
# chgrp [-R] groupname dirname/filename
-R????????
```

### 2. ???????????

?????????????????????????????????????<3F><>

```html
# chown [-R] ?????:????? dirname/filename
```

### 3. ??????

?????????????????????????????????? 3 ??<3F><>???????????????<3F><>???????????<3F><>????? 4??2??1????????????????????? r??4??w??2??x??1??

```html
# chmod [-R] xyz dirname/filename
```

???????? .bashrc ???????????? -rwxr-xr--??

```html
# chmod 754 .bashrc
```

???????<3F><>??????څ????

```html
# chmod [ugoa]  [+-=] [rwx] dirname/filename
- u???????
- g?????????
- o????????
- a????????
- +????????
- -????????
- =???څ???
```

??????? .bashrc ???????????????<3F><>????

```html
# chmod a+w .bashrc
```

## ???????

?????????<3F><>???????????????<3F><>?????<3F><>????????????????<3F><>????????????? w ??????????????????????

???<3F><>????<3F><>???????????????????????<3F><>?????????????? r ???????????????<3F><>?w ????????????????<3F><>????????????????????????????????????????x ??????????????????????x ????? r ?? w ??????????????????????????????????????????????<3F><>??????????<3F><>??????????

## ?????????

??????????????????<3F><>???????????? 666 ??????? -rw-rw-rw- ??
?????????????????????????????????<3F><>???????????? 777 ??????? drwxrwxrwx??

??????? umask ???????????????????????????????????????????? 002 ??????????????????????? 2 ???????????<3F><>???????????????????????? -rw-rw-r-- ??

## ??????

??????? Linux ???<3F>ѷ<EFBFBD>????????????????Filesystem Hierarchy Standard (FHS) ?<3F><>?? Linux ??????????????????????????

- / (root, ????)
- /usr (unix software resource)????????????????????????????
- /var (variable)???????????????<3F><>????<3F><>??????????

???????????????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/27ace615-558f-4dfb-8ad4-7ac769c10118.jpg)

# ???????

## ??????

1. modification time (mtime)????????????????????
2. status time (ctime)??????????????????????????????
3. access time (atime)????????????????

## ????????????????

### 1. ls

?<3F><>???????????????????????????????<3F><>??????????

```html
# ls [-aAdfFhilnrRSt] file|dir
-a ???<3F><>?????????
-d ?????<3F><>???????
-l ?????????????<3F><>???????????????????????????
```

### 2. cp

?????????

?????????????????????????????????????<3F><>?

```html
cp [-adfilprsu] source destination
-a ?????? -dr --preserve=all ??????????? dr ??<3F><>????????
-d ?????????????????????????????????????????????
-i ?????????????????????????????????
-p ?????????????????????
-r ????????????
-u ??destination ?? source ?????? destination???? destination ????????????????
--preserve=all ?????? -p ??????????????????? SELinux ??????, links, xattr ?????????
```

### 3. rm

?????????

```html
# rm [-fir] ???????
-r ????????
```

### 4. mv

?????????

```html
# mv [-fiu] source destination
# mv [options] source1 source2 source3 .... directory
-f ?? force ????????????????????????????????????????
```

## ??????????

### 1. cat

???????????

```html
# cat [-AbEnTv] filename
-n ????????<3F><>?? ??????????????<3F><>???? -b ??????
```

### 2. tac

?? cat ?????????????????<3F><>???????

### 3. more

????????????????????????????????

### 4. less

?? more ?????

### 5. head

??????????????<3F><>?

```html
# head [-n number] filename
-n ??????????????????????<3F><>????
```

### 6. tail

?? head ????????????????????<3F><>?

### 7. od

??????????????????????????????????????

### 8. touch

??????????????????????

```html
# touch [-acdmt] filename
-a ?? ???? atime
-c ?? ???? ctime?????????????????????????
-m ?? ???? mtime
-d ?? ????????????????????????????????????????? --date="????????"
-t ????????????????????????????????????[YYYYMMDDhhmm]
```

## ????????????

### 1. which

?????????

```html
# which [-a] command
-a ????????????<3F><>???????????<3F><>????
```

### 2. whereis

whereis ??????????????????????????????????????

```html
# whereis [-bmsu] dirname/filename
```

### 3. locate

locate ?????<3F><>????????????????????????

locate ??? /var/lib/mlocate/ ???????????????????????<3F><>??????<3F><>?????????????<3F><>?????????? locate ????????????????????? updatedb ???????????????

```html
# locate [-ir] keyword
-r???????????
```

### 4. find

find ?????????????????????????????

```html
# find filename [option]
```

#### 4.1 ??????<3F><>?????

```html
-mtime  n ???<3F><>??? n ??????????????????????
-mtime +n ???<3F><>??? n ????(???? n ????)????????????
-mtime -n ???<3F><>??? n ?????(?? n ????)????????????
-newer file ?? ?<3F><>??? file ????????
```

+4??4 ?? -4 ?????????<3F><>?????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/658fc5e7-79c0-4247-9445-d69bf194c539.png)

#### 4.2 ???????????????????<3F><>?????

```html
-uid n
-gid n
-user name
-group name
-nouser ???????????????? /etc/passwd ?????
-nogroup????????????<3F><>?????? /etc/group ?????
```

#### 4.3 ??????????????<3F><>?????

```html
-name filename
-size [+-]SIZE??????? SIZE ?????(+)??<3F><>(-)?????????? SIZE ?????<3F><>?c: ???? byte??k: ???? 1024bytes??????????? 50KB??????????????? -size +50k
-type TYPE
-perm mode  ???????????? mode ?????
-perm -mode ???????????? mode ?????
-perm /mode ??????????????? mode ?????
```

# ???????????

## ??????????

????????<3F><>????????????????????????????????????????????????????????????????<3F><>???????????????????????????????????????????????????????????????????

???????????????????

1. superblock????????????????????????? inode ?? block ?????????????????????????????????????????????
2. inode?????????????? inode???????????????????????????????????? block ????
3. block????????????????????????????????? block??

????????????????????????? inode ??????????????????????? block?????????? block ?????????????

????????????????????????? block ????????

Ext2 ???????????????????????????????????? block ????????????????????????????? block ??<3F><>???????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/1974a836-aa6b-4fb8-bce1-6eb11969284a.jpg)

## inode

Ext2 ????????? block ??<3F><>?? 1k??2k ?? 4k ?????????? block ??<3F><>??????????????<3F><>??????? inode ??<3F><>????? 128 bytes??

inode ?<3F><>???????????????? block????????? block ???<3F><>?????????????????????? block??????? inode ??<3F><>???????????????????? block?????????????????????????????????? block ???????<3F><>????????? block ?????????????? block??

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/89091427-7b2b-4923-aff6-44681319a8aa.jpg)

inode ????????????????

- ???????????(read/write/excute)??
- ?????????????????(owner/group)??
- ?????????????
- ????????????????????(ctime)??
- ?????<3F><>??????(atime)??
- ??????????(mtime)??
- ???????????????(flag)???? SetUID...??
- ????????????????? (pointer)??

## ???? inode ?? block

???????????????????? inode ????????? block??block ???????????????????????? inode ????????????????????????? inode ???????????????????????????<3F><>????????????????????????????????<3F><>?????????? w ????<3F><>??

## ????????????????

```html
# ln [-sf] source_filename dist_filename
-s ??????? hard link???? -s ? symbolic link
-f ????????5?????????????????????
```

### 1. ???????

hard link ?????????????????????????????????????????????? inode ?????????????????????????????????????????? 0??

????????????????? Filesystem??????????????????

```html
# ln /etc/crontab .
# ll -i /etc/crontab crontab
34474855 -rw-r--r--. 2 root root 451 Jun 10 2014 crontab
34474855 -rw-r--r--. 2 root root 451 Jun 10 2014 /etc/crontab
```

### 2. ????????

symbolic link ???????? Windows ????????????????????????????????????????????????????????????????????????????????????????

symbolic link ????????????????

```html
# ll -i /etc/crontab /root/crontab2
34474855 -rw-r--r--. 2 root root 451 Jun 10 2014 /etc/crontab
53745909 lrwxrwxrwx. 1 root root 12 Jun 23 22:31 /root/crontab2 -> /etc/crontab
```

# ???????

## ???

Linux ?????<3F><>????????????????????????????

| ????? | ??????? |
| -- | -- |
| \*.Z | compress |
|\*.zip |  zip |
|\*.gz  | gzip|
|\*.bz2 |  bzip2 |
|\*.xz  | xz |
|\*.tar |  tar ???????????????<3F><>?????? |
|\*.tar.gz | tar ????????????????? gzip ????? |
|\*.tar.bz2 | tar ????????????????? bzip2 ????? |
|\*.tar.xz | tar ????????????????? xz ????? |

### 1. gzip

gzip ?? Linux ?????????????????? compress??zip ?? gzip ????????????

???? gzip ?????????????????????

?? 9 ???????????????????<3F><>?

??????? zcat??zmore??zless ??????????????????

```html
$ gzip [-cdtv#] filename
-c ???????????????????????
-d ???????
-t ??????????????????
-v ??????????????
-# ?? # ???????????????????????????????????????????6
```

### 2. bzip2

???? gzip ???????????

??????bzcat??bzmore??bzless??bzgrep??

```html
$ bzip2 [-cdkzv#] filename
-k ??????????
```

### 3. xz

???? bzip2 ???????????

?????????gzip??bzip2??xz ??????????????????????????????????????????????

??????xzcat??xzmore??xzless??xzgrep??

```html
$ xz [-dtlkc#] filename
```

## ???

????????????????????????????????????????????????????????tar ???????????????????????? gip??bzip2??xz ?????????????????

```html
$ tar [-z|-j|-J] [cv] [-f ?????tar???] filename...  ==??????
$ tar [-z|-j|-J] [tv] [-f ???<3F><>?tar???]              ==??
$ tar [-z|-j|-J] [xv] [-f ???<3F><>?tar???] [-C ??]    ==?????
-z ?????zip??
-j ?????bzip2??
-J ?????xz??
-c ?????????????
-t ??????????????????<3F><>?????
-x ??????????????????
-v ???????/???????????<3F><>???????????????????
-f : filename?????????????
-C ?? ?? ??????????????
```

????????????

?????? ?? tar -jcv -f filename.tar.bz2 ???????????????????
?? ??&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;?? tar -jtv -f filename.tar.bz2
?????&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;??tar -jxv -f filename.tar.bz2 -C ??????????

# BASH

??????? shell ?????????????Bash ???? shell ??????

## Bash????

**1. ???????**

?????<3F><>??????<3F><>???<3F><>??????<3F><>??????????????????<3F><>? \~/.bash_history ????<3F><>?????????<3F><>??????<3F><>??????<3F><>

**2. ????????????**

??????tab

**3. ????????**

???? lm ?? ls -al ???????

**4. shell scripts**

**5. ????**

???? ls -l /usr/bin/X\* ?<3F><>? /usr/bin ?????????? X ??????????

## ????????

?????????????????? = ??????????????????????? \$ ????????? \${} ????????????????? echo ???<3F><>

```bash
$ var=abc
$ echo $var
$ echo ${var}
```

????????????<3F><>????????????????????????????????????????????????????????var="lang is \$LANG"????var???? lang is zh_TW.UTF-8??????????????????????????????????????? var='lang is \$LANG'???? var ???? lang is \$LANG??


??????? \`???\` ???? \$(???) ????????????<3F><>????????????????? version=\$(uname -r)???? version ???? 3.10.0-229.el7.x86_64??

??????? export ???????????????????????????????????????????????????<3F><>???????????? Bash ?????????? Bash??

Bash ?????????????????????????????????????????<3F><>?????????????????????????????????????????????????? declare ????

```html
$ declare [-aixr] variable
-a ?? ?????????????
-i ?? ?????????????
-x ?? ?????????????
-r ?? ?????readonly????
```

??? [ ] ??????????<3F><>?????

```bash
$ array[1]=a
$ array[2]=b
$ echo ${array[1]}
```

## ??????????

1. ?????????<3F><>?????????????? /bin/ls ???? ./ls ??
2. ?????????????????<3F><>?
3. ?? Bash ????????????<3F><>?
4. ?? \$PATH ?????????????<3F><>??????????????????????<3F><>?

## ???????????

???????????????????????????????????????????

1. ??????? (stdin) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;??????? 0 ????? < ?? << ??
2. ?????? (stdout)&nbsp;&nbsp;&nbsp;&nbsp;??????? 1 ????? > ?? >> ??
3. ??????????(stderr)??????? 2 ????? 2> ?? 2>> ??

???<3F><>?????????????????????????????????????????????????????

??????????????????????????????????? /dev/null ???????????????

??????????????????????????????????????????????????????????????????????? 2>&1 ???????????????????????????

```bash
$ find /home -name .bashrc > list 2>&1
```

## ???????

??????????????????????????????????????????????????????????????????????????????????????????<3F><>???????????????? | ??????????????<3F><>

```bash
$ ls -al /etc | less
```

### 1. ??????cut

????????????<3F><>???<3F><>?

cut ??????????<3F><>??????????????

```html
$ cut
-d ???????
-f ?????? -d ???????? -f n ????? n ??????
-c ??????????<3F><>???????
```

????1??last ????????????????????????????????

```html
$ last
root pts/1 192.168.201.101 Sat Feb 7 12:35 still logged in
root pts/1 192.168.201.101 Fri Feb 6 12:13 - 18:46 (06:33)
root pts/1 192.168.201.254 Thu Feb 5 22:37 - 23:53 (01:16)

$ last | cut -d ' ' -f 1
```

????2???? export ????????????? 12 ??????????????????

```html
$ export
declare -x HISTCONTROL="ignoredups"
declare -x HISTSIZE="1000"
declare -x HOME="/home/dmtsai"
declare -x HOSTNAME="study.centos.vbird"
.....(???????).....

$ export | cut -c 12
```

### 2. ????????sort??uniq

**sort** ????????

```html
$ sort [-fbMnrtuk] [file or stdin]
-f ???????<3F><><EFBFBD><EFBFBD>
-b ??????????????
-M ?????<3F><>???????????????? JAN, DEC
-n ?????????
-r ??????????
-u ?????? unique ?????????????????
-t ?????????????tab
-k ??????????????
```

??????/etc/passwd ???????? : ?????????????????????

```html
$ cat /etc/passwd | sort -t ':' -k 3
root:x:0:0:root:/root:/bin/bash
dmtsai:x:1000:1000:dmtsai:/home/dmtsai:/bin/bash
alex:x:1001:1002::/home/alex:/bin/bash
arod:x:1002:1003::/home/arod:/bin/bash
```

**uniq** ?????????????????????

```html
$ uniq [-ic]
-i ???????<3F><><EFBFBD><EFBFBD>
-c ?????<3F><>???
```

??????????????????????

```html
$ last | cut -d ' ' -f 1 | sort | uniq -c
1
6 (unknown
47 dmtsai
4 reboot
7 root
1 wtmp
```

### 3. ???????????tee

?????????????????????????<3F><>??? **tee** ??????????????????????????????????????????????? tee ?????????????????????????????

```html
$ tee [-a] file
```

### 4. ?????????tr??col??expand??join??paste

 **tr** ???????????<3F><>???????????????????<3F>I??

```html
$ tr [-ds] SET1 ...
-d ?? ??????? SET1 ????????
```

???????? last ????????????<3F><><EFBFBD><EFBFBD>??????<3F><>??

```html
$ last | tr '[a-z]' '[A-Z]'
```

 **col** ?? tab ?????????????

```html
$ col [-xb]
-x ?? ?? tab ?????????????
```

**expand** ?? tab ??????????????????? 8 ????

```html
$ expand [-t] file
-t ??tab ??????????
```

**join** ????????????????<3F><>???????

```html
$ join [-ti12] file1 file2
-t ????????????????
-i ???????<3F><><EFBFBD><EFBFBD>?????
-1 ????????????????????
-2 ????????????????????
```

**paste** ????????????????

```html
$ paste [-d] file1 file2
-d ????????????? tab
```

### 5. ???????split

**split** ????????????????????

```html
$ split [-bl] file PREFIX
-b ?????<3F><>?????<3F><>?????????<3F><>?????? b, k, m ??
-l ?????????????<3F><>?????
- PREFIX ??????????????????
```

# ??????????????????????

## grep

???????????????????????????

```html
$ grep [-acinv] [--color=auto] ???????? filename
-a ?? ?? binary ????? text ??????????????
-c ?? ???????????
-i ?? ?????<3F><><EFBFBD><EFBFBD>
-n ?? ????<3F><>?
-v ?? ????????????????? ???????? ??????????
--color=auto ??????????????????
```

??????????? the ??????????????????????????? --color=auto ???????????????? Linux ?????????? the ???????

```html
$ grep -n 'the' regular_express.txt
8:I can't finish the test.
12:the symbol '*' is represented as start.
15:You are the best is mean you are the no. 1.
16:The world Happy is the same with "glad".
18:google is the best tools for search keyword
```

??? { ?? } ??????? shell ???????????????????????????????????????<3F>^

```html
$ grep -n 'go\{2,5\}g' regular_express.txt
```

?????????????<3F><>? [???????](https://github.com/00000H/notes/blob/master/notes/%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F.md).

## printf

?????????????

????????????????? printf ????????????? $( ) ?????

```html
$ printf '%10s %5i %5i %5i %8.2f \n' $(cat printf.txt)
    DmTsai    80    60    92    77.33
     VBird    75    55    80    70.00
       Ken    60    90    70    73.33
```

## awk

```html
$ awk '???????? 1{???? 1} ???????? 2{???? 2} ...' filename
```

awk ??<3F><>?????<3F><>????????<3F><>??<3F><>????<3F><>??????<3F><>???????????\$n??n ???<3F><>???? 1 ?????\$0 ???????<3F><>?

???? 1???????????????????? ip

```html
$ last -n 5
dmtsai pts/0 192.168.1.100 Tue Jul 14 17:32 still logged in
dmtsai pts/0 192.168.1.100 Thu Jul 9 23:36 - 02:58 (03:22)
dmtsai pts/0 192.168.1.100 Thu Jul 9 17:23 - 23:36 (06:12)
dmtsai pts/0 192.168.1.100 Thu Jul 9 08:02 - 08:17 (00:14)
dmtsai tty1 Fri May 29 11:55 - 12:11 (00:15)

$ last -n 5 | awk '{print $1 "\t" $3}
```

awk ??????

| ???????? | ???????? |
| -- | -- |
| NF | ??????<3F><>???????? |
| NR | ??????????????????? |
| FS | ??????????????????? |

???? 2??????????????<3F><>????????????<3F><>??????

```html
$ last -n 5 | awk '{print $1 "\t lines: " NR "\t columns: " NF}'
dmtsai lines: 1 columns: 10
dmtsai lines: 2 columns: 10
dmtsai lines: 3 columns: 10
dmtsai lines: 4 columns: 10
dmtsai lines: 5 columns: 9
```

?????????????????????<3F><>?????? ==??

???? 3??/etc/passwd ????????????? UID???? UID <20><>?? 10 ????????<3F><>???

```text
cat /etc/passwd | awk 'BEGIN {FS=":"} $3 < 10 {print $1 "\t " $3}'
root 0
bin 1
daemon 2
```

# vim ??????

![](https://github.com/CyC2018/InterviewNotes/blob/master/pics/341c632a-1fc1-4068-9b9f-bf7ef68ebb4c.jpg)

????????????????????????????????<3F><>?????

| ???? | ???? |
| -- | -- |
| :w | <20><>?????|
| :w! | ???????????????<3F><>???????????????<3F><>???????????????????<3F><>? |
| :q | ??|
| :q! | ???????????|
| :wq | <20><>????????|
| :wq!|  ???<3F><>????????|


# ?<3F><>?????

- ???. ?? ?? ?? Linux ? ?? ?? ?? ?? ? ?? ?? ??[J]. 2009.
- [Linux ??????????????](https://www.ibm.com/developerworks/cn/linux/l-cn-rpmdpkg/index.html)