Changes between Version 2 and Version 3 of Csle2022/Agenda/linuxhandson
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- Nov 27, 2022, 8:21:34 AM (2 years ago)
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Csle2022/Agenda/linuxhandson
v2 v3 22 22 23 23 == Exercise == 24 24 {{{ 25 25 1. Login to your VM. and Display your current directory 26 26 2. Change to /etc directory and display current directory … … 36 36 12. Type ‘pwd’ in different directories 37 37 13. Go to ‘cd /etc’ type ‘pdw’ type ‘ls’ type ‘ls -l’ 38 38 }}} 39 39 40 40 == File Editing == 41 41 42 42 The vi editor is installed on almost every Unix. Linux will very often install vim (vi improved) which is similar. Every system administrator should know vi(m), because it is an easy tool to solve problems. 43 43 44 vi Commands and Tips 44 Command Result 45 46 {{{ 45 47 Open: 46 48 vi filename (fn=filename) … … 102 104 locate [name] finds files in Linux using the file name 103 105 104 106 }}} 105 107 == Practicing with vi == 106 108 … … 115 117 Type something like, 116 118 119 {{{ 117 120 "VI is great! I think I'll be using vi from now on instead of Word” 121 }}} 118 122 119 123 Press <ENTER> to add lines. … … 126 130 Copy a large file to your home directory so that you can play around with some more vi commands. We'll copy over your /etc/sysctl.conf file for this exercise. To do this do: 127 131 132 {{{ 128 133 $ cd 129 134 $ cp /etc/sysctl.conf sysctl.conf.bak 135 }}} 130 136 131 137 Edit the file, but let's start at the bottom of the file: 132 138 139 {{{ 133 140 $ vi + sysctl.conf.bak 141 }}} 134 142 135 143 Go to the first line of the file. Notice the colon (“:”) before the “1”. 136 144 {{{ 137 145 :1 <ENTER> 146 }}} 138 147 139 148 Go to line 10, add a new line, and add in some text: 140 149 150 {{{ 141 151 :10 <ENTER> 142 152 Press the “i” key … … 145 155 ## A sample comment 146 156 ## 157 }}} 147 158 148 159 Delete the three lines you just created: … … 152 163 Save the file, but don’t exit. 153 164 165 {{{ 154 166 :w 155 167 press <ENTER> 168 }}} 156 169 157 170 Practice copying and pasting text. … … 159 172 Go to line 12, copy 3 lines of text, go to the bottom of the file, place the text there: 160 173 174 {{{ 161 175 ESC (go to command mode) 162 176 :12 <ENTER> (go to line 12 of the file) … … 164 178 G (go to the end of the file) 165 179 P (place the contents of the copy buffer here) 180 }}} 166 181 167 182 If want to undo this you would type (in command mode): 168 183 184 {{{ 169 185 u 186 }}} 170 187 171 188 Now let’s exit from the file and not save the few changes we’ve made. 172 189 190 {{{ 173 191 :q! <Enter> 174 175 176 Nano Editor192 }}} 193 194 === Nano Editor === 177 195 178 196 GNU nano is a text editor for Unix-like computing systems or operating environments using a command line interface. It emulates the Pico text editor, part of the Pine email client, and also provides additional functionality. Easy to use and all the commands are given in the editor. 179 197 180 198 To create a new file type nano test.txt 199 181 200 Find and Replace 182 201 {{{ 183 202 Create a file test1.txt 184 203 … … 189 208 Foo 190 209 210 191 211 Replace Foo with Bar 192 212 Command - ESC: %s/Foo/Bar/g … … 206 226 Enter then save and quit 207 227 208 228 }}} 209 229 210 230 == Working with Files == … … 213 233 Files on Linux (or any Unix) are case sensitive. This means that FILE1 is different from file1, and /etc/hosts is different from /etc/Hosts (the latter one does not exist on a typical Linux computer). In Linux everything is considered as a file even a directory is a special kind of file. A small overview of some basic and important file handling commands 214 234 215 • file: The file utility determines the file type. Linux does not use extensions to determine the file type. The command line does not care whether a file ends in .txt or .pdf. As a system administrator, you should use the file command to determine the file type. 216 • cp: To copy a file, use cp with a source and a target argument. 217 o cp -r: To copy complete directories, use cp -r (the -r option forces recursive copying of all files in all subdirectories). 218 o cp -i: To prevent cp from overwriting existing files, use the -i (for interactive) option. 219 • mv: Use to rename a file or to move the file to another directory. 220 • rm: Use to remove files *rm -i:To prevent yourself from accidentally removing a file. *rm -rf:rm -r will not remove non-empty directories. However, rm accepts several options that will allow you to remove any directory. The rm -rf will erase anything 221 235 {{{ 236 * file: The file utility determines the file type. Linux does not use extensions to determine the file type. The command line does not care whether a file ends in .txt or .pdf. As a system administrator, you should use the file command to determine the file type. 237 * cp: To copy a file, use cp with a source and a target argument. 238 * cp -r: To copy complete directories, use cp -r (the -r option forces recursive copying of all files in all subdirectories). 239 * cp -i: To prevent cp from overwriting existing files, use the -i (for interactive) option. 240 * mv: Use to rename a file or to move the file to another directory. 241 * rm: Use to remove files *rm -i:To prevent yourself from accidentally removing a file. *rm -rf:rm -r will not remove non-empty directories. However, rm accepts several options that will allow you to remove any directory. The rm -rf will erase anything 242 }}} 243 {{{ 222 244 Dangerous Command 223 245 … … 227 249 • head/tail:You can use head to display the first ten lines of a file. and tail to display the last ten lines of a file. you can use both commands with -n and specify the number of lines 228 250 • cat:The cat command is one of the most universal tools, yet all it does is copy standard input to standard output. 229 251 }}} 230 252 231 '''Exercise''' 253 == Exercise == 232 254 233 255 Create numbers.txt (Containing ten lines of numbers one to ten) file with cat command. … … 359 381 360 382 361 •Commands preceded with "$" imply that you should execute the command as a general user - not as root.362 •Commands preceded with "#" imply that you should be working as root with "sudo"363 •Commands with more specific command lines (e.g. "RTR-GW>" or "mysql>") imply that you are executing commands on remote equipment, or within another program.383 * Commands preceded with "$" imply that you should execute the command as a general user - not as root. 384 * Commands preceded with "#" imply that you should be working as root with "sudo" 385 * Commands with more specific command lines (e.g. "RTR-GW>" or "mysql>") imply that you are executing commands on remote equipment, or within another program. 364 386 365 387 chmod: Change file read write permission chown: Change the owner of the file chgrp: Change the group of the file … … 418 440 419 441 Change file permission as follows 420 442 {{{ 421 443 $ chmod 044 numbers.txt 422 444 }}} 423 445 Now you have remove read privilege try view the file using cat 424 446 {{{ 425 447 $ chmod 444 numbers.txt 448 }}} 426 449 427 450 Now you have set privilege as read only. Open the file via vi editor and try to edit the file 428 451 Switch to root user 429 452 {{{ 430 453 $ sudo su 431 454 … … 433 456 • Change the ownership and group of the numbers3.txt to root and remove all the privileges from all the other users. 434 457 • Switch back to your user and try to view numbers3.txt and try to edit numbers2.txt 435 458 }}} 436 459 437 460 438 More Linux Commands 439 461 === More Linux Commands === 462 463 {{{ 440 464 who: who command will give you information about who is logged on the system. 441 465 … … 448 472 df -dh: report file system disk space usage 449 473 474 man: Will give you man pages (also called manual pages) on your Unix or Linux computer 475 476 date: Will give you the date and time of the system 477 478 $ date 479 480 To set time zone – type $ timedatectl set-timezone Asia/Colombo 481 482 ln: Use to create links between files. Frequently use with -s to create symbolic links 483 450 484 451 485 452 man: Will give you man pages (also called manual pages) on your Unix or Linux computer453 454 455 456 date: Will give you the date and time of the system457 458 $ date459 460 To set time zone – type $ timedatectl set-timezone Asia/Colombo461 462 ln: Use to create links between files. Frequently use with -s to create symbolic links463 464 465 466 486 ps: report a snapshot of the current processes. frequently use with -aux. 467 487 468 488 }}} 469 489 470 490 … … 473 493 474 494 475 476 495 Get network related information 477 496 {{{ 478 497 netstat -a | more : To show both listening and non-listening sockets. 479 498 netstat -at : To list all tcp ports. … … 482 501 netstat -lt : To list only the listening tcp ports. 483 502 netstat -lu : To list only the listening udp ports. 484 503 }}} 485 504 Checking the network connectivity 486 505 … … 489 508 Ping 8.8.8.8 490 509 Ping google.com 510 511 ping6 2001:4860:4860::8888 512 ping6 google.com 513 491 514 }}} 492 515 … … 494 517 The tracepath command in Linux allows to trace the path to the destination path determining MTU along this path using UDP port or any other ports that will not require any superuser permissions. 495 518 519 {{{ 496 520 tracepath [destination] 521 }}} 497 522 498 523 nslookup is the name of a program that lets an Internet server administrator or any computer user enter a host name (for example, "whatis.com") and find out the corresponding IP address or domain name system (DNS) record. 499 524 500 '''nslookup ac.lk''' 501 502 503 525 {{{ 526 nslookup ac.lk 527 }}} 504 528 505 529 The dig (domain information groper) command is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the queried name server(s). 506 530 507 '''dig ac.lk''' 531 {{{ 532 dig ac.lk 533 }}} 534 535 traceroute command in Linux prints the route that a packet takes to reach the host. This command is useful when you want to know about the route and about all the hops that a packet takes. 536 {{{ 537 traceroute [destination] 538 traceroute ac.lk 539 540 traceroute6 [destination] 541 traceroute6 google.com 542 543 }}} 544 On a Windows machine, this command is called tracert; on Linux and Mac, it's called traceroute. 508 545 509 546 510 547 511 traceroute command in Linux prints the route that a packet takes to reach the host. This command is useful when you want to know about the route and about all the hops that a packet takes.512 513 '''traceroute ac.lk'''514 515 On a Windows machine, this command is called tracert; on Linux and Mac, it's called traceroute.516 517 518 519 548 '''ipconfig''' stands for Internet Protocol Configuration, while ifconfig stands for Interface Configuration. 520 521 '''ifconfig''' 522 523 '''ipconfig''' 524 549 {{{ 550 551 ifconfig, ipconfig 552 553 }}}
