Commands using date (199)

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Display your ${PATH}, one directory per line
This works in bash and zsh. You may also want to alias it, if you need to look at it often... $ alias lpath="echo \$PATH | tr : \\\\n" "\$PATH" to make sure to look at your current $PATH

Send your terminfo to another machine
I frequently use this trick to send my terminal settings to HPUX and older RHEL systems. This is due to the fact that terminfo support for rxvt-unicode (my preferred terminal app) does not exist on many older Linux and Unices.

Compare an archive with filesystem
and you quickly know the files you changed

Find the package that installed a command
Put this one-line function somewhere in your shell init, re-login and try $ whatinstalled This is an elaborate wrapper around "dpkg -S", with numerous safeguards. Symlinks and command aliases are resolved. If the searched command is not an existing executable file or was installed by some other means than dpkg/apt, nothing is printed to stdout, otherwise the package name.

ttyS0 - terminal on serial connection
I actually planned to do this for quite a long time, but since I haven't had any suitable client hardware, I procrastinated this. Now, the old laptop I've got from my dad, features an RS-232 port. So, now that I had technically a client, that I could test my RS-232 connection with, I ordered a null modem cable. There is no RS-232 outlet on my desktop computer directly on the mainboard, but theres a connector on the mainbord, where a RS-232 outlet can be attached to. The outlet will then cover up a PCI slot. # Activating RS-232 Ok, once all cables were in place, I tried to access both RS-232 ports by reading from them directly. They're usually ttyS0 or ttyS1, depending what COM-Port it is. From the file /proc/tty/driver/serial, information about the serial setup can be obtained. A setserial -q /dev/ttyS0 might be usefull as well. Usually, the UART Type is 16550A, on a standard PC. Mine wasn't working though. At leas not right from the start, when I tried to read the interface with cat /dev/ttyS0 I got the following error: # cat /dev/ttyS0 cat: /dev/ttyS0: Input/output error Obviously, the driver couldn't activate the hardware. Reason was, it was deactivated in BIOS. After activating RS-232 there, it worked well. As a last action, I added myself to the uucp group, so I have user permission to the serial lines. It is not necessary for the terminal setup, but a good idea to do so, just for future projects, maybe... # Setting up a terminal Once the Serial line is configured and working properly, it's time to let a terminal run on that port. This is what I added to my /etc/inittab : s0:2345:respawn:/sbin/agetty -L 38400 ttyS0 I added it quite on the top of that file, right below the 'si' statement, mingetty cannot be used for serial connections, it cannot be run in a console, too. I tried it for testing purposes, but the cosole - along with your login program - will log you out, as soon as you log in over your serial line. '-L' means this is a local line, with no carrier signal. 38400 is the standard speed of a Linux console, it might be a bit high, I was told, but it works well. I tested that with some higher values as well (115200) and it worked too, I guess it tepends on things like cable length, etc. Last parameter, is the serial tty to listen on. The terminal type can be specified as an additional parameter at the end of the parameter list, vt102, for instance. This is sometimes required, depending on the client. After finishing editing /etc/inittab, an init q will make the system re-read /etc/inittab and apply changes. The agetty should now be listening on ttyS0. #Setting up a client It's time to establish a connection and test the serial line. I use a laptop, that has an RS-232 port, so some preliminary setup is required. I tried minicom as terminal initially, but it turned out, not to be the best client. It initializes the modem, this lasts quite long, and it doesn't convey ANSI colors. So the better option is cu, it's part of the UUCP-Package. Oh, and the serial port of that computer, has to be accessible as well, of course. Once everything was set up, I established the connection: $ cu -l ttyS0 -38400 --nostop Pretty self explanatory, I think. The --nostop option disables XON/XOFF handling. # root access over ttyS0 In order to become root over the serial terminal, the tty needs to be added to /etc/securetty I appended ttyS0 to the end of the file. It is now possible, to gain root access over the serial terminal. The agetty process needs to be restarted to apply changes. # Accessing GRUB over ttyS0 To make bootloader access possible over ttyS0, some changes to /boot/grub/menu.lst need to be done. (GRUB is the bootloader I use, I suppose LiLo has similar capabilities.) Those are the lines, I appended to the top of my menu.lst : serial --unit=0 --speed=38400 --word=8 --parity=no --stop=1 terminal --timeout=3 serial console The serial command initiates the serial terminal option, --unit=0 defines our first serial connector, I my case, it's the only one I have on my machine. I used the standard Linux-Console speed, as well as the "8N1" connection strategy. terminal defines the terminal priorities, first terminal (serial) is the standard one, the last one is the secondary terminal (console). --timeout=3 enables a delay on both consoles, with a prompt for a keystroke. Depending on which terminal, the key is pressed, this terminal, will be used. If no key is pressed after the timeout, the standard console (in my case serial) will be used. # Relaying Kernel output on boot The Kernel accepts multiple console options, of which the last one, is the standard console, and the one that will be used in Single User mode. These are my Kernel options: title Fedora Core (2.6.20-1.2316.fc5) root (hd0,0) kernel /vmlinuz-2.6.20-1.2316.fc5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet vga=795 console=tty0 console=ttyS0,38400 initrd /initrd-2.6.20-1.2316.fc5.img console=tty0 is the standard console, located on the machine, i.e. monitor and keyboard.

Print a list of all hardlinks in the working directory, recursively
libpurple likes to hardlink files repeatedly. To ignore libpurple, use sed: | sed '/\.\/\.purple/d'

Fix borked character coding in a tty.
Often you find some tty programs are messed up and confused about character encoding - 'man' is a common problem and sometimes displays weird characters for apostrophes, hyphens etc etc. Another class of programs that suffer from this are those that try to use the line drawing characters - eg RedHat's tty system admin functions such as system-config-firewall-tui system-config-network-tui etc. Adding 'LC_ALL=C' fixes most of these problems (as long as you want English! Perhaps speakers of other languages can add a comment here). For bonus points, I've added the '-c' option to the man command so that it ignores it's cache and re-computes the man page using the C locale.

Random colours at random locations

List your installed Firefox extensions

Play Mediafile in multipart RAR archive on the fly with buffer to seek back and forth
Fire this up in the directory of the RAR achived files to watch any archived movie tv-show or other media without having to unpack it. I also added a cache/buffer to be able to seek back and forth.


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