quick start of linux programming

Abstract

This article recorded some useful fundamental commands that I came across at the beginning of my linux learning.

第一章 Linux 文件管理

  • 目录结构
  • 列表显示 ls
  • 打开目录 cd
  • 查看文档 cat
  • 创建新文件或心目录
  • 删除命令 rm
  • 改名与移动 mv
  • 压缩与解压 tar
  • 查找文件 find
  • 查找文件内容 grep
  • 修改文件权限 chmod

目录结构

名称 解释
/ 根目录
bin 放普通用户的命令
boot linux的核心文件 如mrb镜像 grub启动
dev 硬件 如串口
etc 系统配置文件 如config
lib 存放动态库
mnt 挂载不同设备
proc 存放cpu 内存 硬件信息
sbin 存放超级用户命令
tmp 临时名录 放置临时信息
usr 类似windows的program file 内有src(source),bin,sbin
var 存放变动性信息 log spool cache

绝对路径: 以/起始 如/home/user1/abc.txt
相对路径: user1/abc.txt

列表显示 ls

命令 解释
ls -l 详细列出所有文件, 一般用 ll 也可以
ls -a 显示所有文件 包括隐藏文件
ll -h -h 表示show in a human-friend way
  • linux中 所有以点开头的文件都是隐藏的文件
  • TAB 敲两次 出现所有可能结果
  • Linux命令执行机制：翻译+执行 如ls 系统先执行ls=ls –color 然后在执行ls –color alias ls=ls可设置回来
    再比如 alias ubuntu=ls 这样执行ubuntu这条命令时 系统会把ubuntu解释成ls
  • 查找某一命令的详解，使用man，比如 
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    $ man ls
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$ ll -h
total 228K
drwx------ 10 lin lin 4.0K Mar 22 15:29 ./
drwxrwxr-x  4 lin lin 4.0K Mar  5 14:57 ../
drwx------  2 lin lin 4.0K Mar 21 15:21 android/
-rw-rw-r--  1 lin lin  18K Mar 17 16:17 break_vigenere.md
drwxrwxr-x  2 lin lin 4.0K Mar 19 22:56 computer_system/
-rw-------  1 lin lin  463 Mar  5 14:13 France.md
drwx------  2 lin lin 4.0K Mar  5 14:13 French_Learning/

第一列：d表示目录 -表示文件
第二到第九十列：r读 w写 x执行 -表示对应的rwx无权限 第一个rwx表示文件所有者权限，第二个表示组权限 第三个表示其他用户权限
第一个lin表示用户 第二个lin表示用户所在组 后面数字表示文件或是目录大小

打开目录 cd

命令 解释
cd 回到home目录
cd .. 回到上层目录
cd - 回到之前所在目录
pwd 显示当前目录

./ 表示当前目录
../ 表示上一级目录

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$ pwd
/home/lin
$ cd /usr/local/MATLAB/
$ pwd
/usr/local/MATLAB/
$ cd -
/home/lin
$ pwd
/home/lin
$ cd ..
$ pwd
/home
$ cd
$ pwd
/home/lin

查看文档 cat

命令 解释
cat filename 在终端查看文档
head filename 在终端查看文档，前十行
head -n filename 在终端查看文档，前n行
tail filename 在终端查看文档，后十行
tail -n filename 在终端查看文档，后n行
cat filename_1 >> filename_2 将文档输出至filename_2的末尾
cat filename_1 > filename_2 将文档输出至filename_2(覆盖) 
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$ head -2 hello.txt 
hello, this is line 1
hello, this is line 2

$ tail -2 hello.txt 
hello, this is line 11
hello, this is line 12

创建新文件或新文件夹

命令 解释
touch filename 创建名为filename的新文档
mkdir foldername 创建名为foldername的新文件夹
mkdir -p folder/new_folder1/new_folder2 创建多级新文件夹 
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$ mkdir hello
$ cd hello/
$ pwd
/home/lin/Dropbox/hello
$ ls
$ mkdir -p hello_01/hello_02
$ ls
hello_01
$ ls hello_01/
hello_02

删除命令 rm

命令 解释
rm filename 删除某一文件
rm -r foldername 或rmdir 删除某一文件夹
rm * 删除当前目录下所有文件 
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$ ll
total 24
drwxrwxr-x 3 lin lin 4096 Mar 22 15:59 ./
drwxrwxr-x 3 lin lin 4096 Mar 22 15:59 ../
drwxrwxr-x 2 lin lin 4096 Mar 22 15:59 hello_02/
$ rm -r hello_02/
$ ll
total 16
drwxrwxr-x 2 lin lin 4096 Mar 22 16:04 ./
drwxrwxr-x 3 lin lin 4096 Mar 22 15:59 ../

改名与移动 mv

命令 解释
mv filename_1 filename_2 将filename_1文件重命名为filename_2
mv filename_1 ../filename_2 将filename_1文件移动至上层目录并重命名为filename_2 
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$ touch hello.txt
$ mv hello.txt ../hello_02.txt 
$ ls hello.txt
ls: cannot access hello.txt: No such file or directory
$ ls ../hello_02.txt 
../hello_02.txt
$ mv ../hello_02.txt ./hello.txt
$ ls ../hello_02.txt 
ls: cannot access ../hello_02.txt: No such file or directory
$ ls hello.txt 
hello.txt

压缩与解压 tar

命令 解释
tar -zcvf {.tgz-file} {files} 将{file}压缩为{.tgz-file}，c代表compress
tar -zxvf {.tgz-fiile} 将{.tgz-file} 解压到当前文件夹 
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$ ls AITR-720.pdf 
AITR-720.pdf
$ tar -zcvf test.tar.gz AITR-720.pdf 
$ ls test.tar.gz 
test.tar.gz

查找文件 find

命令 解释
find {folder} -name “string“ 在{folder}目录下查找文件名含有string的文件 
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$ find ./ -name "*android*"
./android
./android/android_forum.md
./android/android_theory.md

查找文件内容 grep

命令 解释
grep “string” ./* 在当前目录下（不含子目录）查找含有string内容的文件
grep -r “string” ./* 在当前目录下（含子目录）查找含有string内容的文件
grep -rn “string” ./* 在当前目录下（含子目录）查找含有string内容的文件,并打印行号 
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$ grep -rn "hello" test/*
1:this is an example of grep, i want to find "hello"

修改文件权限 chmod

这里先复习以下ls命令

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$ ll
total 12
drwxrwxr-x 2 lin lin 4096 Mar 22 22:24 ./
drwxr-xr-x 4 lin lin 4096 Mar 22 22:25 ../
-rw-rw-r-- 1 lin lin   66 Mar 22 22:24 hello.txt

第二到第九十列：r读 w写 x执行 -表示对应的rwx无权限 第一个rwx表示文件所有者权限，第二个表示组权限 第三个表示其他用户权限。若用二进制加以区分不同的权限的话，111（即十进制的7）代表可读可写可执行，110（即十进制的6）代表可读可写但是不可执行，以此类推。

命令 解释
chmod 权限值 文件名 给文件赋以相应的权限，如chmod 666 hello.txt,表示所有用户都可对hello.txt进行读写操作 
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$ chmod 666 hello.txt 
$ ll
total 12
drwxrwxr-x 2 lin lin 4096 Mar 22 22:24 ./
drwxr-xr-x 4 lin lin 4096 Mar 22 22:25 ../
-rw-rw-rw- 1 lin lin   66 Mar 22 22:24 hello.txt

第二章 Linux 信息查询

查看计算机信息

查看cpu信息：sudo cat /proc/cpuinfo
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$ sudo cat /proc/cpuinfo
[sudo] password for lin: 
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 23
model name	: Intel(R) Core(TM)2 Duo CPU     T6670  @ 2.20GHz
stepping	: 10
microcode	: 0xa07
cpu MHz		: 2201.000
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 0
cpu cores	: 2
apicid		: 0
initial apicid	: 0
fdiv_bug	: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm ida dtherm tpr_shadow vnmi flexpriority
bogomips	: 4400.21
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model		: 23
model name	: Intel(R) Core(TM)2 Duo CPU     T6670  @ 2.20GHz
stepping	: 10
microcode	: 0xa07
cpu MHz		: 1200.000
cache size	: 2048 KB
physical id	: 0
siblings	: 2
core id		: 1
cpu cores	: 2
apicid		: 1
initial apicid	: 1
fdiv_bug	: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm ida dtherm tpr_shadow vnmi flexpriority
bogomips	: 4400.21
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:
查看内存：sudo cat /proc/meminfo
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$ sudo cat /proc/meminfo
MemTotal:        4148372 kB
MemFree:         2393300 kB
MemAvailable:    2967936 kB
Buffers:          108336 kB
Cached:           678276 kB
SwapCached:            0 kB
Active:          1135536 kB
Inactive:         434344 kB
Active(anon):     793392 kB
Inactive(anon):    41728 kB
Active(file):     342144 kB
Inactive(file):   392616 kB
Unevictable:         672 kB
Mlocked:             672 kB
HighTotal:       3284648 kB
HighFree:        1934244 kB
LowTotal:         863724 kB
LowFree:          459056 kB
SwapTotal:       4193276 kB
SwapFree:        4193276 kB
Dirty:               108 kB
Writeback:             0 kB
AnonPages:        783936 kB
Mapped:           354852 kB
Shmem:             51856 kB
Slab:              80168 kB
SReclaimable:      59848 kB
SUnreclaim:        20320 kB
KernelStack:        3736 kB
PageTables:        12036 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     6267460 kB
Committed_AS:    4394972 kB
VmallocTotal:     122880 kB
VmallocUsed:       52848 kB
VmallocChunk:      38164 kB
AnonHugePages:    231424 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:      108536 kB
DirectMap2M:      800768 kB
查看分区：sudo fdisk -l
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$ sudo fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000bd319

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048   616753151   308375552   83  Linux
/dev/sda2       616755198   625141759     4193281    5  Extended
/dev/sda5       616755200   625141759     4193280   82  Linux swap / Solaris
查看显卡：lspci
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$ lspci
00:00.0 Host bridge: NVIDIA Corporation MCP79 Host Bridge (rev b1)
00:00.1 RAM memory: NVIDIA Corporation MCP79 Memory Controller (rev b1)
00:03.0 ISA bridge: NVIDIA Corporation MCP79 LPC Bridge (rev b2)
00:03.1 RAM memory: NVIDIA Corporation MCP79 Memory Controller (rev b1)
00:03.2 SMBus: NVIDIA Corporation MCP79 SMBus (rev b1)
00:03.3 RAM memory: NVIDIA Corporation MCP79 Memory Controller (rev b1)
00:03.5 Co-processor: NVIDIA Corporation MCP79 Co-processor (rev b1)
00:04.0 USB controller: NVIDIA Corporation MCP79 OHCI USB 1.1 Controller (rev b1)
00:04.1 USB controller: NVIDIA Corporation MCP79 EHCI USB 2.0 Controller (rev b1)
00:06.0 USB controller: NVIDIA Corporation MCP79 OHCI USB 1.1 Controller (rev b1)
00:06.1 USB controller: NVIDIA Corporation MCP79 EHCI USB 2.0 Controller (rev b1)
00:08.0 Audio device: NVIDIA Corporation MCP79 High Definition Audio (rev b1)
00:09.0 PCI bridge: NVIDIA Corporation MCP79 PCI Bridge (rev b1)
00:0b.0 SATA controller: NVIDIA Corporation MCP79 AHCI Controller (rev b1)
00:0c.0 PCI bridge: NVIDIA Corporation MCP79 PCI Express Bridge (rev b1)
00:15.0 PCI bridge: NVIDIA Corporation MCP79 PCI Express Bridge (rev b1)
00:16.0 PCI bridge: NVIDIA Corporation MCP79 PCI Express Bridge (rev b1)
02:00.0 VGA compatible controller: NVIDIA Corporation GT218M [GeForce 310M] (rev a2)
02:00.1 Audio device: NVIDIA Corporation High Definition Audio Controller (rev a1)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 03)
04:00.0 Network controller: Qualcomm Atheros AR9285 Wireless Network Adapter (PCI-Express) (rev 01)
查看USB接口：lsusb
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$ lsusb
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 04f2:b071 Chicony Electronics Co., Ltd 2.0M UVC Webcam / CNF7129
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
查看驱动：lsmod
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$ lsmod
Module                  Size  Used by
psmouse                91236  0 
pci_stub               12550  1 
vboxpci                22896  0 
vboxnetadp             25636  0 
vboxnetflt             27291  0 
vboxdrv               300552  3 vboxnetadp,vboxnetflt,vboxpci
bnep                   18895  2 
rfcomm                 58045  0 
bluetooth             391253  10 bnep,rfcomm
6lowpan_iphc           18262  1 bluetooth
nvidia               9704627  55 
uvcvideo               71465  0 
videobuf2_vmalloc      13048  1 uvcvideo
videobuf2_memops       13170  1 videobuf2_vmalloc
videobuf2_core         48344  1 uvcvideo
v4l2_common            15132  1 videobuf2_core
videodev              131265  3 uvcvideo,v4l2_common,videobuf2_core
media                  20899  2 uvcvideo,videodev
mxm_wmi                12893  0 
snd_hda_codec_realtek    70241  1 
snd_hda_codec_generic    62873  1 snd_hda_codec_realtek
snd_hda_codec_hdmi     46396  4 
arc4                   12536  2 
ath9k                 122222  0 
ath9k_common           24878  1 ath9k
ath9k_hw              430710  2 ath9k_common,ath9k
ath                    24182  3 ath9k_common,ath9k,ath9k_hw
mac80211              559049  1 ath9k
coretemp               13201  0 
kvm_intel             137114  0 
snd_hda_intel          29285  5 
kvm                   388518  1 kvm_intel
snd_hda_controller     29944  1 snd_hda_intel
snd_hda_codec         120371  5 snd_hda_codec_realtek,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_intel,snd_hda_controller
snd_hwdep              13272  1 snd_hda_codec
snd_pcm                87194  4 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel,snd_hda_controller
snd_seq_midi           13324  0 
joydev                 17113  0 
snd_seq_midi_event     14475  1 snd_seq_midi
snd_rawmidi            25722  1 snd_seq_midi
cfg80211              418839  4 ath,ath9k_common,ath9k,mac80211
snd_seq                56592  2 snd_seq_midi_event,snd_seq_midi
snd_seq_device         14137  3 snd_seq,snd_rawmidi,snd_seq_midi
serio_raw              13251  0 
snd_timer              28648  2 snd_pcm,snd_seq
snd                    66670  21 snd_hda_codec_realtek,snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_pcm,snd_seq,snd_rawmidi,snd_hda_codec_generic,snd_hda_codec,snd_hda_intel,snd_seq_device
shpchp                 32143  0 
soundcore              14599  2 snd,snd_hda_codec
video                  19475  0 
i2c_nforce2            13050  0 
wmi                    18689  1 mxm_wmi
asus_laptop            23914  0 
sparse_keymap          13708  1 asus_laptop
mac_hid                13059  0 
input_polldev          14247  1 asus_laptop
drm                   255469  3 nvidia
parport_pc             32021  0 
ppdev                  17391  0 
lp                     13299  0 
parport                40836  3 lp,ppdev,parport_pc
hid_logitech_dj        18077  0 
usbhid                 47035  0 
hid                    95946  3 usbhid,hid_logitech_dj
r8169                  61579  0 
mii                    13654  1 r8169
ahci                   25622  2 
libahci                26970  1 ahci
查看kernel版本：uname -r
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$ uname -r
3.16.0-31-generic

$ cat /proc/version
Linux version 3.16.0-31-generic (buildd@lamiak) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #41~14.04.1-Ubuntu SMP Wed Feb 11 19:30:43 UTC 2015

$ uname -a
Linux lin-K40IE 3.16.0-31-generic #41~14.04.1-Ubuntu SMP Wed Feb 11 19:30:43 UTC 2015 i686 i686 i686 GNU/Linux
查看ubuntu版本：sudo cat /etc/issue
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$ cat /etc/issue
Ubuntu 14.04.2 LTS \n \l
查看目录容量 du -h 如du /home -h
命令 解释
du -h 查看当前目录大小
du {folder} -h 查看{foulder}文件夹的大小 
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$ du -h
64K	./android
36K	./Image_Processing
24K	./Windows
24K	./French_Learning
68K	./Linux
52K	./computer_system
16K	./Programming
16K	./matlab
472K	.

$ du ./Linux/ -h
68K	./Linux/
查看硬盘详细信息 hdparm
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$ sudo fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000bd319

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048   616753151   308375552   83  Linux
/dev/sda2       616755198   625141759     4193281    5  Extended
/dev/sda5       616755200   625141759     4193280   82  Linux swap / Solaris

$ sudo hdparm -tT /dev/sda1

/dev/sda1:
 Timing cached reads:   1970 MB in  2.00 seconds = 985.40 MB/sec
查看系统信息：dmesg
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##$ dmesg | more   ## | more 是分小段显示
[    0.000000] Initializing cgroup subsys cpuset
[    0.000000] Initializing cgroup subsys cpu
[    0.000000] Initializing cgroup subsys cpuacct
[    0.000000] Linux version 3.16.0-31-generic (buildd@lamiak) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #41~14.04.1-Ubuntu SMP Wed Feb 11 
19:30:43 UTC 2015 (Ubuntu 3.16.0-31.41~14.04.1-generic 3.16.7-ckt5)
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
查看本次开机运行时间：uptime
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$ uptime
 22:34:02 up  1:00,  3 users,  load average: 0.63, 0.60, 0.52
查看登录信息 last
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$ last | more
lin      pts/11       :0               Mon Mar 23 22:16   still logged in   
lin      pts/0        :0               Mon Mar 23 22:15   still logged in   
lin      :0           :0               Mon Mar 23 21:34   still logged in   
reboot   system boot  3.16.0-31-generi Mon Mar 23 21:33 - 22:34  (01:01)    
lin      pts/8        :0               Mon Mar 23 20:01 - down   (00:00)    
lin      pts/8        :0               Mon Mar 23 19:51 - 20:01  (00:10)

查看进程

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$ ps aux | more
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0   4600  3752 ?        Ss   21:33   0:01 /sbin/init
root         2  0.0  0.0      0     0 ?        S    21:33   0:00 [kthreadd]
root         3  0.1  0.0      0     0 ?        S    21:33   0:07 [ksoftirqd/0]
root         5  0.0  0.0      0     0 ?        S<   21:33   0:00 [kworker/0:0H]
root         7  0.4  0.0      0     0 ?        S    21:33   0:17 [rcu_sched]
root         8  0.0  0.0      0     0 ?        S    21:33   0:00 [rcu_bh]
lin       1766  0.0  0.0   4240   268 ?        Ss   21:34   0:00 //bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session
lin       1778  0.1  0.0   5048  3276 ?        Ss   21:34   0:06 dbus-daemon --fork --session --address=unix:abstract=/tmp/dbus-C1wqkhxGdv
lin       1789  0.0  0.0   4920  2076 ?        Ss   21:34   0:00 upstart-event-bridge

root and lin 都是用户， pid代表进程ID号，可以通过kill PID 来强制结束某个进程。
也可以用top命令：

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$ top

top - 22:39:00 up  1:05,  3 users,  load average: 0.82, 0.65, 0.55
Tasks: 199 total,   2 running, 197 sleeping,   0 stopped,   0 zombie
%Cpu(s):  2.9 us,  0.7 sy,  0.0 ni, 96.0 id,  0.2 wa,  0.0 hi,  0.3 si,  0.0 st
KiB Mem:   4148372 total,  1954148 used,  2194224 free,    49900 buffers
KiB Swap:  4193276 total,        0 used,  4193276 free.   692576 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                    
 2105 lin       20   0  448600 136012  75324 S   2.3  3.3   2:27.26 compiz                                                                     
 1122 root      20   0  350200 146452  47920 S   2.0  3.5   1:12.27 Xorg                                                                       
 2839 lin       20   0  145148  33336  27404 S   2.0  0.8   0:28.74 gnome-terminal                                                             
   13 root      20   0       0      0      0 S   1.3  0.0   0:49.85 ksoftirqd/1                                                                
 2252 lin       20   0  454396 102052  41972 S   1.3  2.5   2:30.96 dropbox

查看历史命令 history

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$ history        #show history commands
$ history -c    #clear history commands in terminal (就是没办法通过向上键得到上一条命令)

如果想history命令也输出时间戳，执行下面的命令，再执行history

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export HISTTIMEFORMAT="%F %T "

可以在终端用Ctrl＋R搜索历史命令，快速！
注:看到你想要的命令后按下左键或者右键,就可以在执行这条命令之前编辑它了］

默认情况下，命令历史被储存在.bash_history文件中，即使$ history -c ，历史也还在。

Linux 用户管理

创建用户

删除用户

用户权限管理

用户组

Linux 网络管理

ping命令

ifconfig 相关命令

配置网卡的IP地址
配置网卡的硬件地址
将网卡禁用 　　ifconfig eth0 down
将网卡启用 　　ifconfig eth0 up
不带参数的ifconfig 命令可以显示当前启动的网络接口
重启网卡

route 命令

使用ssh

Linux 编程基础

环境变量env的查看与修改

环境变量是一个具有特定名字的对象，它包含了一个或者多个应用程序所将使用到的信息。例如PATH，当要求系统运行一个程序而没有告诉它程序所在的完整路径时，系统除了在当前目录下面寻找此程序外，还应到PATH中指定的路径去找。用户通过设置环境变量，来更好的运行进程。
终端输入env查看所有的环境变量。

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$ env
ORBIT_SOCKETDIR=/tmp/orbit-bearthur
SSH_AGENT_PID=1486
TERM=xterm
SHELL=/bin/bash
XDG_SESSION_COOKIE=c7856cbb97b9b99b583752ea00000007-1298359229.627829-1075292124
GST_ID3V2_TAG_ENCODING=GBK:UTF-8:GB18030
WINDOWID=81788933
GNOME_KEYRING_CONTROL
...(这里省略很多行)

有时候编译程序需要设置新的环境变量：export 环境变量=新值 //
比如： export DISPLAY =”localhost:0.0” 要加” “， 赋值时=两边不要加空格

需求例子： 我按装好了matlab，但是每次想启动matlab的时候都要跑到/usr/local/MATLAB/R2010b/bin目录下去执行” ./matlab”,我想直接就敲matlab启动。
解决方法： 把matlab的路径添加到修改环境变量PATH。

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$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
$ matlab
matlab: command not found
$ export PATH=$PATH:"/usr/local/MATLAB/R2010b/bin"
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/MATLAB/R2010b/bin
$ matlab

重启电脑，发现再执行matlab还是command not found，查看PATH发现PATH已经恢复为原来的值了。这是因为上面的修改只是临时修改，如果想永久修改环境变量的值。需要修改~/.bashrc文件。

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$ vi .bashrc      // 往最后一行添加export PATH=$PATH:"/usr/local/MATLAB/R2010b/bin"
$ source .bashrc  //使生效

参考：ubuntu 环境变量修改和恢复总结

使用Ctags快速查看代码

nano编辑器

vi编辑器

编辑模式；命令模式；ex模式。
按esc键可以转到命令模式，按很多键可以转到编辑模式（比如i），按”：”可以进入ex模式, 前面带”:”的都是ex命令。

常见命令
命令 解释
vi hello.cpp 进入vi编辑器，编辑hello.cpp文件
光标的移动 上下左右，enter键。或是：左（h）；右（l，空格键）；上（k）；下（j）
:w 保存
:q 退出
:wq 保存并退出
:q! 退出（不保存）
i 在当前光标前插入字符
a 在当前光标后插入字符
A 跳到行末尾进行编辑
o(小写字母o) 在当前行下面插入一行
O(大写字母O) 在当前行上面插入一行
x或nx（n代表数字） 从当前光标处往右删除（剪切）一个或n个字符
D或dd 剪切整行
Y或y 复制整行
nyy (n代表数字) 向下复制n行，同理，向下剪切n行为ndd
/hello 或?hello 搜索hello这个词，再按”n”向后查找，”N”向前查找
u,U(大写：回退到进入本行后的所有操作) 撤销命令
:se nu 查看行号（debug的时候经常用到，用来定位出错行）
:se nonu 隐藏行号
:%s/hello/bye/g 把所有的”hello”都变成”bye”

gcc编译器

编译
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$ vi max.c
$ gcc -c max.c
$ ls max.o
max.o
链接
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$ gcc max.o -o run
$ ll run
-rwxrwxr-x 1 lin lin 7394 May  5 00:02 run*
静态链接库的编译链接

静态链接库在链接后，被引用的代码讲被复制到最终的可执行文件中，可脱离函数库直接运行。

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bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1.c lib src
bear@bear-K40IE:~/program/sec$ ar rv libtools.a add.o
ar: creating libtools.a
a – add.o
bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1.c lib libtools.a src
bear@bear-K40IE:~/program/sec$ vi sub.c
bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1.c lib libtools.a src sub.c
bear@bear-K40IE:~/program/sec$ gcc -c -O sub.c
bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1.c lib libtools.a src sub.c sub.o
bear@bear-K40IE:~/program/sec$ ar rv libtools.a sub.o
a - sub.o
bear@bear-K40IE:~/program/sec$ mv libtools.a ./lib

bear@bear-K40IE:~/program/sec/lib$ vi my.h
bear@bear-K40IE:~/program/sec/lib$ ls
libtools.a my.h
bear@bear-K40IE:~/program/sec$ vi first1.c
bear@bear-K40IE:~/program/sec$ gcc -c -I./ first1.c
bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1.c first1.o lib my.h src sub.c sub.o
bear@bear-K40IE:~/program/sec$ gcc -c first1.c
ear@bear-K40IE:~/program/sec$ gcc first1.o -L./lib -ltools -o first1
bear@bear-K40IE:~/program/sec$ ls
add.c add.o first1 first1.c first1.o lib my.h src sub.c sub.o
bear@bear-K40IE:~/program/sec$ ./first1
VALUE+10=110
VALUE-10=90
bear@bear-K40IE:~/program/sec$ gcc first1.o -o first1
first1.o: In function `main':
first1.c:(.text+0x19): undefined reference to `add'
first1.c:(.text+0x48): undefined reference to `sub'
collect2: ld returned 1 exit status

这是add.c文件：

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#include <stdio.h>
int add(int a,int b)
{
  return a+b;
}

这是sub.c文件:

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#include<stdio.h>
int sub(int a,int b)
{
  return a-b;
}

这是first1.c文件：

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#include<stdio.h>
#include"my.h"
main ()
{

  fprintf(stderr,"VALUE+10=%d\n",add(VALUE ,10));
  fprintf(stderr,"VALUE-10=%d\n",sub(VALUE ,10));
}

动态链接库的编译链接

动态链接库在内存中只包含一份可执行的映像，所有链接到动态链接库的程序都共享这份映像！

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bear@bear-K40IE:~/program/third$ vi first.c
bear@bear-K40IE:~/program/third$ gcc -fPIC -c first.c
bear@bear-K40IE:~/program/third$ ls
first.c first.o
bear@bear-K40IE:~/program/third$ file first.o
first.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped
bear@bear-K40IE:~/program/third$ gcc -shared -o libabc.so first.o
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so
bear@bear-K40IE:~/program/third$ vi hello.c
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so hello.c
bear@bear-K40IE:~/program/third$ gcc -c hello.c -O
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so hello.c hello.o
bear@bear-K40IE:~/program/third$ gcc hello.o -L./ -labc -s hello
gcc: hello: No such file or directory
bear@bear-K40IE:~/program/third$ echo LD_LIBRARY_PATH
LD_LIBRARY_PATH
bear@bear-K40IE:~/program/third$ export LD_LIBRATY_PATH=./
bear@bear-K40IE:~/program/third$ gcc hello.o -L./ -labc -s hello
gcc: hello: No such file or directory
bear@bear-K40IE:~/program/third$ gcc hello.o -labc -s hello #少了个-o
gcc: hello: No such file or directory
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so hello.c hello.o
bear@bear-K40IE:~/program/third$ gcc hello.o -labc -s -o hello
/usr/bin/ld: cannot find -labc
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so hello.c hello.o
bear@bear-K40IE:~/program/third$ echo LD_LIBRARY_PATH #少了个$
LD_LIBRARY_PATH
bear@bear-K40IE:~/program/third$ export LD_LIBRATY_PATH="./"
bear@bear-K40IE:~/program/third$ echo LD_LIBRARY_PATH
LD_LIBRARY_PATH
bear@bear-K40IE:~/program/third$ echo $LD_LIBRARY_PATH

bear@bear-K40IE:~/program/third$ export LD_LIBRATY_PATH=./ #注意拼写啊！
bear@bear-K40IE:~/program/third$ echo $LD_LIBRARY_PATH

bear@bear-K40IE:~/program/third$ echo $LD_LIBRARY_PATH

bear@bear-K40IE:~/program/third$ export LD_LIBRARY_PATH=./
bear@bear-K40IE:~/program/third$ echo $LD_LIBRARY_PATH
./
bear@bear-K40IE:~/program/third$ gcc hello.o -L./ labc -s -o hello
gcc: labc: No such file or directory
bear@bear-K40IE:~/program/third$ gcc hello.o -L./ -labc -s -o hello
bear@bear-K40IE:~/program/third$ ls
first.c first.o libabc.so hello hello.c hello.o
bear@bear-K40IE:~/program/third$ ./hello
240 is the result

这是first.c文件：

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#include <stdio.h>
int fx(int a,int b)
{
  return a*b;
}

这是hello.c文件：

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#include <stdio.h>
main()
{
  fprintf(stderr,"%d is the result \n",fx(10,24));
}

如何写makefile文件

demo_1: 有多个C++类与一个main函数，普通写法(直观)
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all: human.o point.o beast.o nature.o fight.o log.o random.o
        g++ random.o beast.o nature.o point.o fight.o human.o log.o -Wall -g -o run -lstdc++ -lm
human.o: human.cc human.h point.h global.h
        g++ -c human.cc -lstdc++ -lm
fight.o: fight.cc
        g++ -c fight.cc -lstdc++ -lm
point.o: point.cc point.h
        g++ -c point.cc -lstdc++ -lm
beast.o: beast.cc beast.h point.h
        g++ -c beast.cc -lstdc++ -lm
nature.o: nature.cc nature.h
        g++ -c nature.cc -lstdc++ -lm
log.o: log.h log.cc
        g++ -c log.cc -lstdc++ -lm
random.o: random.h random.cc
        g++ -c random.cc -lstdc++ -lm 
clean:
        rm *.o
demo_2: 有多个依赖于OpenCV的C++类与一个main函数， 高级写法
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CC      = g++
CFLAGS  = -Wall -g
INFLAGS = -I/usr/local/include/opencv -I/usr/include/opencv2
LFLAGS  = -L/usr/local/lib/
SRC     = Main.cpp ObjDet.cpp
OBJ     = $(SRC:.cpp=.o)
TARGET  = run
DEPEND  = -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_stitching -std=c++11
.cpp.o:
        $(CC) -c $(INFLAGS) $(CFLAGS) $(SRC) 
$(TARGET): $(OBJ)
        $(CC) $(LFLAGS) $(OBJ) -o $(TARGET) $(DEPEND)
clean:
        rm *.o

使用gdb调试程序

shell基础

Github的使用

使用Markdown写技术博客

Linux下MySQL的使用

常用的Linux快捷键

常见linux问题及解决办法