Say you want to execute 'file' on the command 'top' (to determine what type of file it is); but you don't know where 'top' resides: preface the argument with = and zsh will implicitly prepend the path.

Sometimes it is handy to be able to list contents of a tar file within a compressed archive, such as 7Zip in this instance, without having to extract the archive first. This is especially helpful when dealing with larger sized files.

say you want to edit your PATH variable using bash/zsh commandline editing, this will put something like this in history so you can edit it:

PATH=/bin:/usr/bin:/usr/sbin

to make this a shell function such that:

eev HOME

will put /home/dave in the last history event:

eev()

{

print -s "$1='$(eval echo \$$1)'"

}

Don't track in history commands starting with whitespace.

Moreover ignore duplicates from history.

To be set in .bashrc

ex.

$ export HISTCONTROL=ignoreboth

$   echo antani

$   history|grep -c antani

say you've just found all the config files with this command

find . -name '*.config'

and you need to edit them all

vi `!!`

will re-execute the command and present them to vi in the argument list

don't use if the list is really long as it may overflow the command buffer

grep's -c outputs how may matches there are for a given file as "file:N", cut takes the N's and awk does the sum.

I often use "vim -p" to open in tabs rather than buffers.

You got some results in two variables within your shell script and would like to find the differences? Changes in process lists, reworked file contents, ... . No need to write to temporary files. You can use all the diff parameters you'll need. Maybe anything like $ grep "^>"

is helpful afterwards.

Let dd use direct I/O to write directly to the disk without any caching. You'll encounter very different results with different block sizes (try with 1k, 4k, 1M, ... and appropriate count values).

This will create the file /tmp/pkgdetails, which will contain a listing of all the files installed on your RPM-based system (RedHat, Fedora, CentOS, etc). Useful should the RPM system/database become corrupted to find which package installed which files.

Note, the [remotePort] should be opened in the firewall first. First, start the destination box listening, then fire off the sending box. Data from the /dev/zero device in memory of the source machine is read out using dd, sent over the network with nc, and read back in from the other side of the network with nc, going to the /dev/null device. Essentially, it is a memory-network-memory copy operation, the output of dd will tell you how fast your network really is performing.

In Debian based distros, this command will list 'binutils' package details which contains 'nm' command. You can replace 'nm' to any other command.

Depending on the speed of you system, amount of RAM, and amount of free disk space, you can find out practically how fast your disks really are. When it completes, take the number of MB copied, and divide by the line showing the "real" number of seconds. In the sample output, the cached value shows a write speed of 178MB/s, which is unrealistic, while the calculated value using the output and the number of seconds shows it to be more like 35MB/s, which is feasible.

Scan for open ports on the target device/computer (192.168.0.10) while setting up a decoy address (192.168.0.2). This will show the decoy ip address instead of your ip in targets security logs. Decoy address needs to be alive. Check the targets security log at /var/log/secure to make sure it worked.

ps command gives the possibility to display information with custom formatting with the -o options followed by the format specifier list.

Redirects the contents of your clipboard through a pipe, to a remote machine via SSH.

Using 7z to create archives is OK, but when you use tar, you preserve all file-specific information such as ownership, perms, etc. If that's important to you, this is a better way to do it.

greps using only ascii, skipping the overhead of matching UTF chars.

Some stats:

$ export LANG=C; time grep -c Quit /var/log/mysqld.log

7432

real 0m0.191s

user 0m0.112s

sys 0m0.079s

$ export LANG=en_US.UTF-8; time grep -c Quit /var/log/mysqld.log

7432

real 0m13.462s

user 0m9.485s

sys 0m3.977s

Try strace-ing grep with and without LANG=C

I've used technicalpickles command a lot, but this one handles whitespaces in filenames. I'm sure you want to create an alias for it :)

Just a handy way to get all the unique links from inside all the html files inside a directory. Can be handy on scripts etc.