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| cmdchallenge.com |
Gần đây tôi biết đến một trang web thú vị là Command Challenge. Đúng như tên gọi của nó, trang này có những thử thách dưới dạng dòng lệnh Bash Shell. Vừa hay tôi cũng đang tìm hiểu về Bash Shell vì vậy mà tôi sẽ viết writeup để lưu giữ những kiến thức đã học được.
1. Your first challenge is to print “hello world” on the terminal in a single command.
echo "hello world"
Kết quả:
hello world
2. Print the current working directory.
pwd
Kết quả:
/var/challenges/current_working_director
3. List names of all the files in the current directory, one file per line.
ls
Kết quả:
01-take.txt 02-the.txt 03-command.txt 04-challenge.txt
cat access.log
Kết quả:
163.56.115.58 - - [09/Jan/2017:22:29:57 +0100] "GET /posts/2/display HTTP/1.0" 200 3240 75.113.188.234 - - [09/Jan/2017:22:30:43 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 1116 69.16.40.148 - - [09/Jan/2017:22:34:33 +0100] "GET /pages/create HTTP/1.0" 500 3471 225.219.54.140 - - [09/Jan/2017:22:35:30 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 500 2477 207.243.19.2 - - [09/Jan/2017:22:38:03 +0100] "GET /bar/create HTTP/1.0" 200 1116 199.37.62.156 - - [09/Jan/2017:22:42:18 +0100] "GET /posts/1/display HTTP/1.0" 200 2477 55.74.240.123 - - [09/Jan/2017:22:44:25 +0100] "POST /posts/1/display HTTP/1.0" 200 3471 251.111.109.143 - - [09/Jan/2017:22:49:02 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 2477 101.163.230.250 - - [09/Jan/2017:22:52:31 +0100] "DELETE /posts/2/display HTTP/1.0" 404 2477 200.19.168.148 - - [09/Jan/2017:22:57:11 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 3471
5. Print the last 5 lines of "access.log".
tail -5 access.log
Kết quả:
199.37.62.156 - - [09/Jan/2017:22:42:18 +0100] "GET /posts/1/display HTTP/1.0" 200 2477 55.74.240.123 - - [09/Jan/2017:22:44:25 +0100] "POST /posts/1/display HTTP/1.0" 200 3471 251.111.109.143 - - [09/Jan/2017:22:49:02 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 2477 101.163.230.250 - - [09/Jan/2017:22:52:31 +0100] "DELETE /posts/2/display HTTP/1.0" 404 2477 200.19.168.148 - - [09/Jan/2017:22:57:11 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 3471
6. Create an empty file named take-the-command-challenge in the current working directory.
touch take-the-command-challenge
7. Create a directory named tmp/files in the current working directory
Hint: The directory “tmp/" doesn't exist, with one command you need to create both "tmp/" and "
tmp/files"mkdir -p tmp/files
8. Copy the file named take-the-command-challenge to the directory tmp/files
cp take-the-command-challenge tmp/files/take-the-command-challenge
9. Move the file named take-the-command-challenge to the directory tmp/files
mv take-the-command-challenge tmp/files/take-the-command-challenge
10. A symbolic link is a type of file that is a reference to another file.
Create a symbolic link named take-the-command-challenge that points to the file tmp/files/take-the-command-challenge.
ln -s tmp/files/take-the-command-challenge "take-the-command-challenge"
11. Delete all of the files in this challenge directory including all subdirectories and their contents.
Hint: There are files and directories that start with a dot ".", "rm -rf *" won't work here!
find -delete
12. There are files in this challenge with different file extensions. Remove all files with the .doc extension recursively in the current working directory.
find . -name "*.doc" -delete
13. There is a file named access.log in the current working directory. Print all lines in this file that contains the string "GET".
grep GET access.log
Kết quả:
163.56.115.58 - - [09/Jan/2017:22:29:57 +0100] "GET /posts/2/display HTTP/1.0" 200 3240 75.113.188.234 - - [09/Jan/2017:22:30:43 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 1116 69.16.40.148 - - [09/Jan/2017:22:34:33 +0100] "GET /pages/create HTTP/1.0" 500 3471 225.219.54.140 - - [09/Jan/2017:22:35:30 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 500 2477 207.243.19.2 - - [09/Jan/2017:22:38:03 +0100] "GET /bar/create HTTP/1.0" 200 1116 199.37.62.156 - - [09/Jan/2017:22:42:18 +0100] "GET /posts/1/display HTTP/1.0" 200 2477 251.111.109.143 - - [09/Jan/2017:22:49:02 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 2477 200.19.168.148 - - [09/Jan/2017:22:57:11 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 3471
14. Print all files in the current directory, one per line (not the path, just the filename) that contain the string "500".
grep -l 500 *
Kết quả:
access.log access.log.1
15. Print the relative file paths, one path per line for all filenames that start with "access.log" in the current directory.
ls
Kết quả:
access.log access.log.1 access.log.2
16. Print all matching lines (without the filename or the file path) in all files under the current directory that start with "access.log" that contain the string "500".
Note that there are no files named access.log in the current directory, you will need to search recursively.
grep -rh 500
Kết quả:
69.16.40.148 - - [09/Jan/2017:22:34:33 +0100] "GET /pages/tạo HTTP/1.0" 500 3471 225.219.54.140 - - [09/Jan/2017:22:35:30 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 500 2477 2.71.250.27 - - [09/Jan/2017:22:41:26 +0100] "GET/trang/tạo HTTP/1.0" 500 2477
17. Extract all IP addresses from files that start with "access.log" printing one IP address per line.
grep -ro ^[0-9.]*
Kết quả:
var/log/httpd/access.log:163.56.115.58 var/log/httpd/access.log:75.113.188.234 var/log/httpd/access.log:69.16.40.148 var/log/httpd/access.log:225.219.54.140 var/log/httpd/access.log:207.243.19.2 var/log/httpd/access.log:199.37.62.156 var/log/httpd/access.log:55.74.240.123 var/log/httpd/access.log:251.111.109.143 var/log/httpd/access.log:101.163.230.250 var/log/httpd/access.log:200.19.168.148 var/log/httpd/access.log.1:108.68.174.15 var/log/httpd/access.log.1:17.2.20.139 var/log/httpd/access.log.1:28.151.137.59 var/log/httpd/access.log.1:199.150.241.179 var/log/httpd/access.log.1:2.71.250.27 var/log/httpd/access.log.1:17.137.186.194 var/log/httpd/access.log.1:151.84.119.34 var/log/httpd/access.log.1:4.180.204.195 var/log/httpd/access.log.1:9.230.96.54 var/log/httpd/access.log.1:157.143.233.21
18. Count the number of files in the current working directory. Print the number of files as a single integer.
grep -ro ^[0-9.]*
Kết quả: Correct!
19. Print the contents of access.log sorted.
sort access.log
Kết quả:
101.163.230.250 - - [09/Jan/2017:22:52:31 +0100] "DELETE /posts/2/display HTTP/1.0" 404 2477 163.56.115.58 - - [09/Jan/2017:22:29:57 +0100] "GET /posts/2/display HTTP/1.0" 200 3240 199.37.62.156 - - [09/Jan/2017:22:42:18 +0100] "GET /posts/1/display HTTP/1.0" 200 2477 200.19.168.148 - - [09/Jan/2017:22:57:11 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 3471 207.243.19.2 - - [09/Jan/2017:22:38:03 +0100] "GET /bar/create HTTP/1.0" 200 1116 225.219.54.140 - - [09/Jan/2017:22:35:30 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 500 2477 251.111.109.143 - - [09/Jan/2017:22:49:02 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 2477 55.74.240.123 - - [09/Jan/2017:22:44:25 +0100] "POST /posts/1/display HTTP/1.0" 200 3471 69.16.40.148 - - [09/Jan/2017:22:34:33 +0100] "GET /pages/create HTTP/1.0" 500 3471 75.113.188.234 - - [09/Jan/2017:22:30:43 +0100] "GET /posts/foo?appID=xxxx HTTP/1.0" 200 1116
20. Print the number of lines in access.log that contain the string "GET".
grep -ro ^[0-9.]*
Kết quả:
