Xensoft

CLI

Re-call Command Line Arguments in BASH

BASH's history expansion character, ! has many features, including !: for choosing a specific argument (or range of arguments) from the history. The gist is any number after !: is the number of the argument you want, with !:1 being the first argument and !:0 being the command. echo one two three one

CLI

Simple Way to Get your External IP on the Command Line

This is an easy way to see what IP a website is seeing you come from: curl httpbin.org/ip { "origin": "52.11.93.181" } curl icanhazip.com 52.11.93.181 Lots of other options, but these are some of the shortest I've seen.

CLI

Google text-to-speech in MP3 Format via the Command Line

The function will take a string and create an MP3 of the string being spoken and named after the first 15 characters of the string: t2s() { wget -q -U Mozilla -O $(tr ' ' _ <<< "$1"| cut -b 1-15).mp3 "http://translate.google.com/translate_tts?ie=UTF-8&tl=en&q=

CLI

A Couple Ways to Identify the Shell you're Using

ps -p $$ PID TTY TIME CMD 76146 ttys002 0:54.05 -bash echo $SHELL /bin/bash The first gets the PID and command of the current shell, the second is an environment variable that should be set in most shells.

CLI

List DEBs by Size

dpkg-query -Wf '${Installed-Size}\t${Package}\n' | sort -n Similar the the RPM [https://xensoft.com/find-the-largest-installed-rpms/] equivalent. However, the above doesn't seem to always list the "Installed Size" - you can always fall back to this brute force method: dpkg --get-selections | cut -f1 | while read pkg; do dpkg -L

CLI

Use Multiple CPU Cores(Parallelize) with Single Threaded Linux Commands

Note: If things are not working as described below check the version information for parallel. parallel --version WARNING: YOU ARE USING --tollef. IF THINGS ARE ACTING WEIRD USE --gnu. ... Either add --gnu to all your parallel commands, or edit /etc/parallel/config and make sure it lists --gnu and not

CLI

Unpacking or Repacking initrd.img or initramfs.img

Need to tinker with an initrd.img or initramfs.img? Here are the steps to unpack these files and then put them back together again if you've made any changes. First step, make a copy of the initrd.img or initramfs.img in question: cp /boot/initramfs-*.img /tmp The

Bash

Advanced BASH Variable Usage

Basic Variable Usage * $VARIABLE * ${VARIABLE} BASH variables are case sensitive, e.g. $VARIABLE is not the same as $variable. The curly bracket syntax allows the variable name to be delimited from trailing characters that otherwise might be interpreted as part of the variable name: VARIABLE=end echo "The opposite of

MySQL

Backing up All Databases in MySQL without the Warnings

Backing up MySQL used to be quick, easy and silent using mysqldump, but more recent versions of MySQL produce the following nagging warning: mysqldump -u root -p --all-databases --single-transaction > bak.sql Enter password: -- Warning: Skipping the data of table mysql.event. Specify the --events option explicitly. If you'd like

MySQL

Create a MySQL User for Backups

The following SQL will create a MySQL user with the minimum number of privileges necessary to backup databases: CREATE USER 'backup'@'localhost' IDENTIFIED BY '#PASSWORD#'; GRANT SELECT, RELOAD, FILE, SUPER, LOCK TABLES, SHOW VIEW ON *.* TO 'backup'@'localhost' IDENTIFIED BY '#PASSWORD#' WITH MAX_QUERIES_PER_HOUR

CLI

How a BASH Script Can Find Its Own Location

Most foolproof method I'm aware of is the following: SCRIPTDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd && echo x)" SCRIPTDIR="${SCRIPTDIR%x}" or if you're not worried about newlines at the end of your directory names: SCRIPTDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )" How does this work? In the first example

CLI

Exploring the BASH_SOURCE Array

$BASH_SOURCE is the call stack of scripts with the top of the stack being the currently executing sourced script, sourcing another script from the current one will push it on top of the stack. To get an idea of how this works you can set up a directory tree

CLI

How to Save Only Some Files in a Directory Tree and Delete Strange Filenames

Sometimes a bunch of unwanted files end up somewhere they don't belong. Maybe a cp gone wrong, or other command line typo creates a slew of oddly named files -- but you've got a number of files you'd really like to keep around mixed in with the bad. The following

CLI

Split or Restore only Part of a Complete MySQLdump

If you keep your database backed up into a single SQL dump and want to retrieve only the part matching one database, perhaps to transfer to another system, I find the simplest and most re-usable trick is to use sed's "p" function which prints the "pattern space" to STDOUT even

CLI

Use exec to redirect all BASH script output to a file, syslog, or other command

One of the neat tricks of exec is that you can use it to redirect all output from a shell. If you take advantage of this inside of a script you can easily send all your output to a file, or even syslog. #!/bin/bash # redirect STDOUT to a file

CLI

The Instagram of Code

Feel left out of the Instagram craze? Everyone else is sharing pictures of their food and all you have is code. Not to worry InstaCode [http://instacod.es] has you covered: [http://instacod.es/79356]

CLI

Visualize the Return Code of Your Last Command via the Prompt

I like to have a pretty obvious indication of the success of failure of any commands I might have run. To accomplish this I add several color coding shortcuts to my .bash_profile: RED='\033[0;31m' GREEN='\033[0;32m' BLUE='\033[0;34m' NOFORMAT='\

Perl

What does "use strict;" in Perl do?

What does use strict; in Perl really get you? By default three things, which can be specified separately or turned off separately: # All on by default when using use strict; use strict "vars"; use strict "subs"; use strict "refs"; # One or more can be turned off if need be no

Bash

Print out Line Numbers in a BASH Script

The environment variable $LINENO contains the current line number of the running BASH shell. On the command line the value will be the number of command line prompts you've used in that shell, but in a script it's the currently executing line -- and it really is line number, if

Perl

Return Multiple Values from a Hash in any Order using Slices

Usually when you access a hash you get a single scalar value back, but it's also possible to get an array of values back - a slice of the hash. To do this all you have to do is pass in an array of keys, rather then a single key,

CLI

Install Dropbox via the CLI

I decided to refresh my Dropbox install on Fedora 17 (now Fedora 18) from scratch and found the documentation of how to do that from the CLI a little conflicted. Here are the steps that worked for me. Run the following commands as the user you want to be your

Backups

Get rsync like Functionality with Amazon's S3

I'm currently using s3sync [http://s3sync.net/wiki%22], a ruby script that gives rsync like functionality with Amazon's S3 service, to store some of my more irreplaceable data. However it looks like maintenance of the program has become a bit spotty. The latest updated version can be found on

CLI

Easily Search Commands in your BASH History

Create your ~/.inputrc or append it with the following: "\\e[A": history-search-backward "\\e[B": history-search-forward set show-all-if-ambiguous on set completion-ignore-case on Now when you start typing a command you can use the up and down arrows to search for commands you previously used that started the same way: vim↑ vim

CLI

"No valid Xcode installation is properly selected" solved

I needed to download the CLI tools within Xcode, and it needs to be done before installing MacPorts -- otherwise you'll need to re-install MacPorts. So I launched Xcode and went to "Preferences > Downloads" and clicked install on " Command Line Tools." Installed MacPorts from the dmg package on googlecode, but

CLI

The Dangers of Copying and Pasting Commands from the Internet

What you see on a webpage isn't necessarily what you get when you copy something off it. Watch out for extra hidden logic, especially in "example commands" you might copy directly over to a prompt. The command below demonstrates the point, and is safe to run. It just doesn't do