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`-r script.m` also possible
defines a handy function for quick calculations from cli.
once defined:
$ ? 10*2+3
only for sudo-style systems.
Use this construct instead of I/O re-directors ``>'' or ``>>'' because
sudo only elevates the commands and *not* the re-directors.
***warning: remember that the `tee` command will clobber
file contents unless it is given the ``-a'' argument
Also, for extra security, the "left" command is still run unprivileged.
Simply makes it possible to launch any X application residing on sshhost through sshproxy and display it on your screen where ever you are.
Run the alias command, then issue
$ps aux | tail
and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand.
$ ${LINES:-`tput lines 2>/dev/null||echo -n 12`}
Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the default of 80.
The default for TAIL is to output the last 10 lines, this alias changes the default to output the last x lines instead, where x is the number of lines currently displayed on your terminal - 7. The -7 is there so that the top line displayed is the command you ran that used TAIL, ie the prompt.
Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux/bash-power-prompt.html )
275MB/748MB
[7995:7993 - 0:186] 06:26:49 Thu Apr 08 [askapache@n1-backbone5:/dev/pts/0 +1] ~
$
In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device.
This one-liner will use strace to attach to all of the currently running apache processes output and piped from the initial "ps auxw" command into some awk.
I know its not much but is very useful in time consuming scripts (cron, rc.d, etc).