All commands

Allows you to change the value of an environment variable only for the execution of the command in the line. (corrected)

Seems obvious, but other seemingly simple ways to use it don't work:

and

both output:

and this:

outputs:

with the slash :(

you can also do any combinations of quotes for a complex string:

outputs:

prints a random line

This command is great for dumping your history so that when you're working on a system that is under a shared account, you can keep others from reviewing your history file. I use this when I'm just visiting a system to diagnose a problem, or to make a quick fix.

Change /dev/sda with the Disk or partition you want to back-up

To restore use:

Once again change /dev/sda accordingly

Source: http://www.go2linux.org/linux/2010/09/small-tip-back-disks-clone-hard-disk-773

see http://www.imagemagick.org/Usage/color_mods/#modulate

the maven.test.skip property can be added to other goals too.

Searching for a String in Multiple Files With Grep

compile and install openvm-tools module in debian lenny

This is useful when you got a reserved IP address like 192.168.0.100 and want to find out what IP address is used to access the Internet. You have to know a server with 'efingerd -n' configured, like www.linuxbanks.cn as above.

Other method to find out this information are for example access www.tell-my-ip.com and grep the output. The finger method have the advantage that it is easy to deploy a service like www.tell-my-ip.com, as you only need to get efingerd installed.

Usefull e.g. in krusader open terminal function

Perfect time for the rarely used sub shell.

Display the machine "hardware name" 32 or 64 bit.

"x86_64" is shown on 64 bit machines

"i686" is typically shown on 32 bit machines (although, you might also see "i386" or "i586" on older Linuxen).

On other "unix-like" systems, other hardware names will be displayed.

For example, on AIX, "uname -m" gives the "machine sequence number".

For whatever reason, IBM decided that "uname -M" would give the machine type and model.

(ref: http://www.ibm.com/developerworks/aix/library/au-aix-systemid.html )

On Sun Solaris, "uname -m" can be used to determine the chip type and "isainfo -v" will reveal

if the kernel is 64 or 32 bit.

(ref: http://www.ibiblio.org/pub/packages/solaris/sparc/html/32.and.64.bit.packages.html )

A more reliable way to determine "64-bit ness" across different Unix type systems is to compile the following simple C program:

/*

* program bits.c

* purpose Display "32" or "64" according to machine type

* written January 2013

* reference http://www.unix.org/whitepapers/64bit.html

*/

/* hmm, curious that angle-brackets removed by commandlinefu.com data input processing? */

#include "/usr/include/stdio.h"

long lv = 0xFFFFFFFF;

main ( ) {

printf("%2d\n",(lv < 0)?32:64);

}

eeooff

Compile and run thusly: cc -o bits bits.c; ./bits

Writes out the shebang line (#!/bin/bash) to the script.

another alternative to encrypt strings

Can pipe to tail or change the awk for for file size, groups, users, etc.

Looks like you're stuck with sed if your ls doesn't have a -Q option.