====== BASH i okolice ====== ===== Kolorowanie tekstu w terminalu i inne tamże sztuczki ===== Here is some more detail on the awesome tput command suggested in Ignacio's answer. ==== Colour commands ==== # Set the background colour using ANSI escape tput setab [1-7] # Set the foreground colour using ANSI escape tput setaf [1-7] Colours are as follows: Num Colour #define RGB 0 black COLOR_BLACK 0,0,0 1 red COLOR_RED max,0,0 2 green COLOR_GREEN 0,max,0 3 yellow COLOR_YELLOW max,max,0 4 blue COLOR_BLUE 0,0,max 5 magenta COLOR_MAGENTA max,0,max 6 cyan COLOR_CYAN 0,max,max 7 white COLOR_WHITE max,max,max There are also non-ANSI versions of the colour setting functions (''setb'' instead of ''setab'', and ''setf'' instead of ''setaf'') which use different numbers, not given here. ==== Text mode commands ==== tput bold # Select bold mode tput dim # Select dim (half-bright) mode tput smul # Enable underline mode tput rmul # Disable underline mode tput rev # Turn on reverse video mode tput smso # Enter standout (bold) mode tput rmso # Exit standout mode tput sgr 0 # Reset all attributes ==== Cursor movement commands ==== tput cup Y X # Move cursor to screen postion X,Y (top left is 0,0) tput cuf N # Move N characters forward (right) tput cub N # Move N characters back (left) tput cuu N # Move N lines up tput ll # Move to last line, first column (if no cup) tput sc # Save the cursor position tput rc # Restore the cursor position tput lines # Output the number of lines of the terminal tput cols # Output the number of columns of the terminal ==== Clear and insert commands ==== tput ech N # Erase N characters tput clear # Clear screen and move the cursor to 0,0 tput el 1 # Clear to beginning of line tput el # Clear to end of line tput ed # Clear to end of screen tput ich N # Insert N characters (moves rest of line forward!) tput il N # Insert N lines ==== Other commands ==== tput bel # play a bell With [[https://extensions.gnome.org/extension/669/wobbly-windows/|compiz wobbly windows]], the ''bel'' command makes the terminal wobble for a second to draw the user's attention. ==== Example usage ==== ''echo "$(tput setaf 1)Red text $(tput setab 7)and white background$(tput sgr 0)"'' Looks like this on my Ubuntu terminal: {{:linux:4stug.png?200|}} Use command ''sgr 0'' to reset the colour at the end. ==== Performing multiple operations at once ==== ''tput'' accepts scripts containing one command per line, which are executed in order before tput exits. Avoid temporary files by echoing a multiline string and piping it: echo -e "setf 7\nsetb 1" | tput -S # set fg white and bg red ==== See also ==== * See ''[[http://unixhelp.ed.ac.uk/CGI/man-cgi?tput+1|man 1 tput]]'' * See ''[[http://www.manpagez.com/man/5/terminfo/|man 5 terminfo]]'' for the complete list of commands and more details on these options. (The corresponding tput command is listed in the Cap-name column of the huge table that starts at line 81.) ===== Backup bashem ===== http://www.cyberciti.biz/faq/how-to-wakeup-backup-nas-server-and-mirror-files-using-rsync-in-linux/ ===== Ciekawostki ===== ==== Federico Bento ''Terminal escape sequences'' ==== So recently i've encountered a post by Kurt Seifried of RedHat on oss-sec's mailing list entitled //[[http://www.openwall.com/lists/oss-security/2015/08/11/8|"Terminal escape sequences - the new XSS for admins?"]]// This is a little misleading title, since escape sequences have been introduced circa 70's, so it's actually not that new. How it technically works: A terminal escape sequence is a special sequence of characters that is printed (like any other text). If the terminal understands the sequence, it won't display the character-sequence, but will perform some action. While some people might already know what i'm going to present you, the majority I believe doesn't, so this is mostly to raise awareness. $ printf '#!/bin/bash\necho doing something evil!\nexit\n\033[2Aecho doing something very nice!\n' > backdoor.sh $ chmod +x backdoor.sh $ cat backdoor.sh #!/bin/bash echo doing something very nice! $ ./backdoor.sh doing something evil! As you can see, our beloved ''cat'' cheated on us. Why? Because instead of displaying the character-sequence, the escape sequence **''\033[XA''** (being ''X'' the number of times) performed some action. And this action moves the cursor up ''X'' times, overwriting what is above it ''X'' lines. But this doesn't affect only '**cat**', it affects everything that interprets escape sequences. $ head backdoor.sh #!/bin/bash echo doing something very nice! $ tail backdoor.sh #!/bin/bash echo doing something very nice! $ more backdoor.sh #!/bin/bash echo doing something very nice! It's not over yet! $ curl 127.0.0.1/backdoor.sh #!/bin/bash echo doing something very nice! $ wget -qO - 127.0.0.1/backdoor.sh #!/bin/bash echo doing something very nice! But if we pipe it into a shell... $ curl -s 127.0.0.1/backdoor.sh|sh doing something evil! $ wget -qO - 127.0.0.1/backdoor.sh|sh doing something evil! You might be thinking //"If I opened that in my browser, I would detect it being malicious!"// Well, think again... One can have all sorts of fun with user-agents, something that can easily come to mind is verifying if the user-agent is from curl or wget, and make them download the malicious file, if not, redirect them to a legitimate file that looks like the original output. Your browser would fool you then. I wouldn't even be surprised if most of those install scripts that make use of these ''pipe into sh'' bullcrap abused this. I wouldn't even be surprised if most of you were already pwned by escape sequences in any situation at all. Imagine the possibilities, from hidden ssh keys on your authorized_keys to options hidden on your configuration files... It's no secret, most of us rely on ''cat'' to view files. I guess this is one black kitty, giving you bad luck. Here's another example with a ''.c'' file $ printf '#include \n\nint main()\n{\n\tprintf("doing something evil\\n");\n\t/*\033[2A\n\t/* This simple program doesnt do much... */\n\tprintf("doing something very nice\\n");\n\treturn 0;\n}\n' > nice.c $ cat nice.c #include int main() { /* This simple program doesnt do much... */ printf("doing something very nice\n"); return 0; } $ gcc nice.c $ ./a.out doing something evil doing something very nice ''diff'' also interprets escape sequences and so do the resulting patches Going back to the first example, imagine I have a ''backdoored.sh'' that is backdoored, and a legit.sh that does what it's output tells us. $ cat backdoor.sh #evil file #!/bin/bash echo doing something very nice! $ cat legit.sh #actually echoes doing something very nice! #!/bin/bash echo doing something very nice! $ diff -Naur backdoor.sh legit.sh --- backdoor.sh 2015-09-17 16:25:42.985349535 +0100 +++ legit.sh 2015-09-17 16:26:14.950158635 +0100 @@ -1,4 +1,2 @@ #!/bin/bash -echo doing something very nice! +echo doing something very nice! $ diff -Naur backdoor.sh legit.sh > file.patch $ patch legit.sh -R file.patch $ chmod +x legit.sh $ ./legit.sh doing something evil! === Hint: === ''less'' doesn't interpret escape sequences unless the ''-r'' switch is used, so stop aliasing it to ''less -r'' just because there's no colored output. s/party/hack like it's 1999