divesh2201/shell-commands

shell-commands-cheatsheet

Bourne-again shell (Bash) is a command line language interpreter for the GNU OS.

Linux is GUI with optional command line while Unix is only command line

1. strings: see the text inside a binary/data file

   -n <length>: specify the length of strings we want, default 4

2. open: open an image in preview

3. exiftool: working with metadata on command line

4. binwalk: searches a binary image for embedded files and executable code

5. chmod: change mod is used to change permissions for a file eg: chmod +x is adding execute permissions (- is remove, = is assign, etc)

6. ls -ld: lists permissions (10 digit) first digit represents 'd' for directory and '-' for file next 9 are split into three 3's, owner, group and world eg: drwxr-xr-x, so here we have read write and execute permissions as owner

7. curl/wget: client URL / www get - allows you to exchange data between server and cli

8. man: manual for a command, eg: man binwalk

9. grep: global regular expression print, to search matching patterns in a file

10. 2>/dev/null: redirect the stderr (>) to and don't print on terminal (/dev/null supressing the output, null)

11. 2?&1: redirect stderr to stdout, & tells shell that 1 is not a filename but file descriptor (file descriptor 1 is stdout, 2 is stderr)

12. --: is used to denote end of flags. eg: you want to mkdir -q (-q is the name of the directory), then mkdir -- -q

13. s is for scrolling down (macOS) (j for parrotOS) and k for scrolling up inside man, use /<search> for searching your flag

14. cat <file_name(s)> reads and prints contents of a file

15. nc: 'NetCat' is like a cat command over a network. It is a networking communication tool used to read and write data to network connections (ports) using TCP/UDP

16. Pager program: helps the user get the output, on the terminal, one page at a time. Popular pagers in Unix are more and less

17. objdump: program for displaying information about object files in Unix, eg: used as a disassembler to view executable in assembly form

18. file command gives information about the file you pass

19. ltrace intercepts and records dynamic library calls, similar strace traces system calls called by a process