Cheatsheet

Check folder size:

du -sh foldername/

Clear trash folder (Ubuntu & friends):

rm -rf ~/.local/share/Trash/files ~/.local/share/Trash/info

Arch Linux guest VM in VirtualBox:

Restore networking:

sudo ip link set enp0s8 down && sudo ip link set enp0s8 up && curl www.google.com

Mount USB drive

Before inserting the USB drive, show list of devices: :

sudo lsblk -f

Insert USB drive, and select device in VirtualBox GUI menu ( Devices > USB > … )

In VM, show list of devices again to find the DEVICENAME of the new device: :

sudo lsblk -f

Mount the device: :

sudo -i
mkdir /mnt/usbstick
mount /dev/DEVICENAME /mnt/usbstick

wget

Mirror site: :

wget -mkE http://www.example.com

Mirror subdirectory of website: :

wget -mkE -np http://www.example.com/subdir/

Mirror full web page: :

wget -pkE -np -nH -nd http://www.example.com/page.html
wget -np -k -p -nd -nH -H -E http://www.example.com/page.html

Related: extract URLs ('http://…' ones) from HTML file: :

sed 's/<a href="/\n/g' index.html | sed 's/">/\n/g' | grep "^http:" | sort -u

youtube-dl

Download video from YouTube: :

youtube-dl "URL"

Download audio from YouTube: :

youtube-dl -x -o "%(title)s.%(ext)s" "URL"

Download audio & convert to mp3: :

youtube-dl -x --audio-format "mp3" -o "%(title)s.%(ext)s" "URL"

Download videos listed in urls.txt: :

cat urls.txt | xargs -I{} youtube-dl "{}"

Download audio of videos listed in urls.txt: :

cat urls.txt | xargs -I{} youtube-dl -x -o "%(autonumber)s - %(title)s.%(ext)s" "{}"

Update program: :

sudo youtube-dl -U

zenity

Zenity menu: :

zenity --width=640 --height=480 --list --column "Number" --column "Name" --title="Numbers and their names" --text="" 1 one 2 two 3 three

Zenity menu from textfile, 1st line is the title, 2nd line are the column names, separated by tab characters, rest of the file are line entries separated by newlines, divided in columns by tab characters: :

eval zenity --width=640 --height=480 --list $(cat menu.txt | sed '2q;d' | tr '\t' '\n' | sed 's/^/--column\ \"/' | sed 's/$/\"/' | tr '\n' ' ') --title=$(cat menu.txt | head -n 1 | sed 's/^/\"/' | sed 's/$/\"/' | tr '\n' ' ') $(cat menu.txt | tail -n +3 | tr '\t' '\n' | sed 's/^/\"/' | sed 's/$/\"/' | tr '\n' ' ')

tail

tail -f /var/log/messages

mount

Mount ext3 partition: :

sudo mkdir /media/bigpart
sudo mount /dev/sda4 /media/bigpart -t ext3

Auto-mount USB drive at startup. Files owned by user with uid==1000. Put this in /etc/fstab:

UUID=5F04-234F /media/USB_HDD auto nosuid,nodev,nofail,uid=1000,gid=1000,umask=022,fmask=133,dmask=022 0 0

Remarks:

The value for UUID can be obtained with the command blkid.
The mount point (in this case /media/USB_HDD) must exist.
The octal permission masks are not the same as in chmod. Subtract every digit from 7 to convert between the two. See table below.

Symbolic	`chmod`	`fstab`
`-rw-r—r--`	644	133
`rwxr-xr-x`	755	022

bash

Redirection in bash

Redirect stderr of command to stdout: :

ls 2>&1

Don’t output anything: :

ls > /dev/null 2>&1

Echo to stderr: :

echo Hello >&2

Iterate over output of command, one line per iteration, and write output to a file: :

while read line; do
    echo Another line: $line
done < <(some_command arg1 arg2) > afile.txt

Send value of a variable as standard input (stdin) to a command, and capture output in another variable: :

$ myvar="one two"
$ yourvar=$(tr ' ' '_' <<<$myvar)
$ echo $yourvar
one_two

Send value of a variable as input to a chain of piped commands, and capture output in another variable: :

$ myvar=abcde
$ yourvar=$(tr 'a' 'b' <<<$myvar | tr 'b' 'c' | tr 'c' 'd')
$ echo $yourvar
dddde

Truncate a file (wipe its contents): :

> myfile.txt

Booleans in bash

hot=true

if $hot; then
    echo "It's hot"
else
    echo "It's cold"
fi

Globbing in bash

Test if glob expands to anything: :

theGlob=*.html
if stat -t $theGlob > /dev/null 2>&1; then
    echo *.html
else
    echo No matches found.
fi

or with "find": :

theGlob=*.html
if [ -n "$(find . -maxdepth 1 -name "$theGlob" -print -quit)" ]; then
    echo *.html
else
    echo No matches found.
fi

Variable assignment in bash

Set the variable logDir to $LOG_DIR, or '~/log' if $LOG_DIR is an empty string: :

logDir=${LOG_DIR:-~/log}

Example: :

$ someVar=foo
$ emptyVar=
$ myVar=${someVar:-bar}
$ yourVar=${emptyVar:-bar}
$ echo myVar = $myVar; echo yourVar = $yourVar
myVar = foo
yourVar = bar

Set the variable myVar to 'foo' if $myVar is an empty string, otherwise leave myVar unchanged :

: ${myVar:=foo}

Example: :

$ myVar=foo
$ yourVar=
$ : ${myVar:=bar}
$ : ${yourVar:=bar}
$ echo myVar = $myVar; echo yourVar = $yourVar
myVar = foo
yourVar = bar

Equivalent of ternary operator in bash: :

[[ "$year" = "leapyear" ]] && numdays=366 || numdays=365

Keyboard shortcuts in bash:

Clear screen: :

ctrl-l

Open editor to write command in: :

Ctrlv-XE

Keyboard shortcuts (from: http://www.getoffmalawn.com/blog/useful-bash-shortcuts): :

Movement
--------

Shortcut        Action
Ctrl-a          Move to the start of the line
Ctrl-e          Move to the end of the line
Ctrl-b          Move back one character
Alt-b           Move back one word
Ctrl-f          Move forward one character
Alt-f           Move forward one word
Ctrl-] x        Move the cursor forward to next occurance of x
Alt-Ctrl-] x    Move the cursor backward to the next occurance of x


Line Modification
-----------------

Shortcut        Action
Ctrl-u          Delete from the cursor to the beginning of the line
Ctrl-k          Delete from the cursor to the end of the line
Esc Backspace   Delete back a word
Alt-d           Delete forward a word
Alt-r           Undo all changes to the line
Ctrl-y          Paste any text deleted with previous shortcuts
Ctrl-e Esc-t    Swap order of the last two arguments


History Utilisation
-------------------

Shortcut        Action
Ctrl-x Ctrl-u   Undo the last change to the line
Ctrl-r          Incremental reverse search of history
Alt-p           Non-incremental reverse search of history
Ctrl-L          Clear the screen (doesn't wipe current line)
!!              Execute last command in history
!abc            Execute last command in history beginning with abc
!n              Execute nth command in history
!$              Last argument of previous command
!^              First argument of previous command
^abc^xyz        Replace first occurance of abc with xyz in previous command and execute it
Alt-. (period)  Paste last word from previous command after cursor position (repeat to cycle through previous commands)

Miscellaneous bash commands:

List commands found in bash history, sorted by usage: :

cat ~/.bash_history | cut -f1 -d' ' | sort | uniq -c | sort -n -r | more

ln

Create hard links in a folder to all files in another folder, eg: :

ln -t ~/.gnome2/nautilus-scripts ~/tools/nautilus/*

Create symbolic link named 'LNK' to target file named 'TGT': :

ln -s TGT LNK

Run command in background and return to shell immediately (e.g. 'firefox index.html'). Don’t write any output to nohup.out. :

nohup firefox index.html > /dev/null 2>&1

tar

Create tar.gz from directory: :

tar cpzf mydir.tar.gz mydir

Extract directory from tar.gz file: :

tar xzf mydir.tar.gz

Check Linux version

cat /etc/issue

lsb_release -a

cat /etc/lsb-release

uname -a

cat /proc/version

Logfiles

Browse syslog with vim (requires https://github.com/bergoid/rabot): :

find /var/log -maxdepth 1 | grep syslog | sort | flon

Batch renaming

Replace a substring 'foo' with 'bar' in all names of textfiles

Output every renaming command for review: :

for filename in *.txt ; do echo mv \"$filename\" \"${filename//foo/bar}\"; done

Execute the reviewed commands: :

for filename in *.txt ; do echo mv \"$filename\" \"${filename//foo/bar}\"; done | /bin/bash

ls, find, grep

List all filenames in directory tree: :

find . -print

or: :

find .

or: :

find $(pwd)

List files in reverse chronological order: :

ls -lt

List the the most recently modified files in directory tree: :

find . -type f -exec stat --format '%Y :%y %n' {} \; | sort -nr | cut -d: -f2- | head

List files in reverse order by size: :

ls -lS

List only filenames: :

ls -m1

Find all files matching '*.c': :

find . -name \*.c

Find directories named 'mydir': :

find . -type d -name mydir

Search for 'pattern' in all .cpp files in 'mydir', recursively: :

grep pattern -nr --include=\*.cpp mydir

Search for 'pattern' in all .cpp and .h files in 'mydir', recursively: :

grep pattern -nr --include=\*.{cpp,h} mydir

Search for 'pattern' in all files in current dir, but don’t recurse into subdirectories: :

grep -d skip pattern *

Replace all occurrences of 'oldstring' with 'newstring' in all .txt files in directory tree rooted in '.':

find . -name '*.txt' -type f -print0 | xargs -0 sed -i 's|oldstring|newstring|g'

Remove all .flac files in directory tree rooted in '.':

find . -name '*.flac' -type f -print0 | xargs -0 rm

Compare 2 directories: print 2 columns of files unique to either directory:

comm -3 <(find dir1 -type f -printf '%f\n' | sort -u) <(find dir2 -type f -printf '%f\n' | sort -u)

directories

cd into parent dir of currently running bash script: :

cd $(dirname $(readlink -f $0))

Lines in files

Output Nth line of file :

more +N file | head -n 1

head -N file | tail -1

Count the number of lines in file: :

wc -l < my_text.txt

Modify files

Remove all blank lines :

cat file.txt | sed '/^\s*$/d' > file2.txt

or in-place: :

sed -i '/^\s*$/d' file.txt

Package management

dpkg

Show (among other info) dependencies of .deb file: :

dpkg -I package_file.deb

Install a .deb file: :

sudo dpkg -i package_file.deb

Uninstall a .deb file: :

sudo dpkg -r package_file.deb

List all installed packages: :

dpkg -l

List files provided by package: :

dpkg -L packagename

pacman

Install a package :

pacman -Syu package_name

Check if a package is installed: :

pacman -Q package_name

List all files owned by an installed package: :

pacman -Ql package_name

Find package that owns a given file :

pacman -Qo file_path

Display info about an installed package: :

pacman -Qi package_name

Display info about a package: :

pacman -Si package_name

Uninstall a package and its orphaned dependencies: :

pacman -Rs package_name

Clean pacman cache ( /var/cache/pacman/pkg ): :

pacman -Scc

List all packages from a given repository (here 'community' as an example): :

paclist community

Print dependency tree of a package: :

pactree packagename

OpenBox

Edit the OpenBox menu: :

vi ~/.config/openbox/menu.xml

Edit the OpenBox settings: :

vi ~/.config/openbox/rc.xml

Go to location of .desktop files: :

cd /usr/share/applications

Reconfigure OpenBox: :

openbox --reconfigure

Make bootable USB stick from .iso file

From: http://crunchbang.org/forums/viewtopic.php?id=23267

Determine what device your USB is. With your USB plugged in run: :

sudo ls -l /dev/disk/by-id/*usb*

This should produce output along the lines of: :

lrwxrwxrwx 1 root root  9 2010-03-15 22:54 /dev/disk/by-id/usb-_USB_DISK_2.0_077508380189-0:0 -> ../../sdb
lrwxrwxrwx 1 root root 10 2010-03-15 22:54 /dev/disk/by-id/usb-_USB_DISK_2.0_077508380189-0:0-part1 -> ../../sdb1

Now cd to where your *.iso is :

cd ~/downloads

Example :

sudo dd if=filename.iso of=/dev/usbdevice; sync

let’s say the iso is named mini.iso and your USB device is sdb

Example :

sudo dd if=mini.iso of=/dev/sdb; sync

vim

Some shortcuts: :

Deleting text:
dd      Delete line
dw      Delete rest of word, until (but excluding) start of next word
D       Delete rest of line (including character under cursor)
d$      "
d0      Delete beginning of line before cursor
x       Delete character
da(     delete a set of matching parens and everything in them
S       substitute line (i.e. replace entire line with an empty line and go to insert mode)
:%s/\s\+$//   delete trailing whitespace on all lines

Inserting text:
i               Insert text before cursor
a               Insert text after cursor
A               Append text to the end of a line
I               Insert text before the first non-blank in the line
C               Replace rest of line
o               Insert new line above cursor
O               Insert new line below cursor
ctrl-v<tab>     Insert tab character even when expandtab is on

:r !ls      Insert output of shell command into text (here: ls)

Transforming text:
ctrl-a    increment number under cursor
ctrl-x    decrement number under cursor

u       undo
ctrl-r  redo

Moving:
g;      jump back to last edited position.
g_      go to last non-whitespace character on line
w       go to start of next word
e       go to end of (next) word
b       go start of (previous) word
W       go to start of next word (words are whitespace-delimited)
E       go to end of word (words are whitespace-delimited)
B       go start of (previous) word (words are whitespace-delimited)
zz  put current line at the center of the screen
zz  move current line to the middle of the screen
zt  move current line to the top of the screen
zb   move current line to the bottom of the screen
Ctrl-e  Moves screen up one line
Ctrl-y  Moves screen down one line
Ctrl-u  Moves screen up ½ page
Ctrl-d  Moves screen down ½ page
Ctrl-b  Moves screen up one page
Ctrl-f  Moves screen down one page

Selecting pieces of text:
vw      select from cursor to start of next word
vb      select from cursor to start of word under cursor
vaw     select word under cursor
vi(     select parens block, parens excluded
va(     select parens block, parens included
vi", vi', vi[, vi<, vi{     analogous as 2 lines higher
va", va', va[, va<, va{     analogous as 2 lines higher
vit     select text between HTML tags
vat     select text between HTML tags, together with the tags themselves

File handling:
:e filename     Open new file in editor
:e! filename    Open new file in editor, discard buffer
:e .                    Browse current directory
:w                      Write buffer
:w filename     Write buffer to filename
:q                      Exit vim
ZZ                      Save buffer and exit vim
:x                      "
ZQ                      Discard buffer and exit vim
:q!                     "

Searching:
/searchstring           search for searchstring
/searchstring\c     case-insensitive search for searchstring

:%s/old/new/g           replace all occurrences of 'old' with 'new'
:%s/\<old\>/new/g   same, but whole word only
:%s/old\c/new/g     replace all case-insensitive matches of 'old' with 'new'
:%s/old/new/gc          replace all occurrences of 'old' with 'new', confirm each substitution
:%s/\t/    /g       replace all tabs with 4 spaces

Tabs:
:set expandtab
:set tabstop=4

Comment all lines of a block
Go to the first line, press ctrl-v, select until last line, press I#<Esc>

Reselect block:
gv

Uncomment all lines of a block
Go to the first line, press ctrl-v, select until last line, press x

Multi-window:
Ctrl-w o    Close all windows except current:
:on        idem
Ctrl-w q    Close current window
Ctrl-w p    Switch to previously accessed window:

Colors:
Show highlight groups with their current color:
:so $VIMRUNTIME/syntax/hitest.vim

scp

Copy the file "foobar.txt" from the local host to a remote host :

scp foobar.txt your_username@remotehost.edu:some/remote/directory

Copy the file "foobar.txt" from a remote host to the local host :

scp your_username@remotehost.edu:foobar.txt some/local/directory

Copy the directory "foo" from the local host to a remote host’s directory "bar" :

scp -r foo your_username@remotehost.edu:some/remote/directory/bar

Copy the directory "foo" from a remote host to the local host’s directory "bar" :

scp -r your_username@remotehost.edu:some/remote/directory/foo bar

apt-get and dpkg

Show info about file.deb: :

dpkg -I file.deb

echo text and redirect to privileged file:

echo 'some text' | sudo tee -a /etc/some.file

Start/stop/enable/disable daemons

Enable the ssh daemon: :

update-rc.d ssh defaults

Disable it: :

update-rc.d -f ssh remove

Start daemon: :

sudo service ssh start

Restart daemon: :

sudo service ssh restart

Stop daemon: :

sudo service ssh stop

List of options for 'setxkbmap':

vi /usr/share/X11/xkb/rules/base.lst

tmux

Create new session: :

$ tmux new -s session-name

Detach from session: :

<CTRL-b> d

Attach to first available session: :

$ tmux a

Attach to specific session: :

$ tmux a -t session-name

Install Oracle Java 7 in Debian Wheezy:

From: http://stackoverflow.com/questions/15543603/installing-java-7-oracle-in-debian-via-apt-get

sudo su

echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list
echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys EEA14886
apt-get update
apt-get install oracle-java7-installer

Git

Create a tag

Create a tag both locally and on the remote:

tagname=MY_TAG && git tag -a $tagname -m "$tagname" && git push origin $tagname

Delete a tag

Delete a tag both on the remote and locally:

tagname=MY_TAG && git push --delete origin $tagname && git tag --delete $tagname

Create a branch

Create a branch both locally and on the remote:

branchname=MY_BRANCH && git checkout -b $branchname && git push -u origin $branchname

Delete a branch

Delete a branch both on the remote and locally:

branchName=MY_BRANCH && git push --delete origin $branchName && git branch --delete $branchName

Revert some of the files in a commit

List all files changed in a commit, select some of them and revert the selected ones to their previous state:

commitHash=320aacfe3ad && git diff-tree --no-commit-id --name-only -r $commitHash | pickn | xr git checkout ${commitHash}~1 --

Show all tags that contain a given commit

git tag --contains HASH

Web project: use Github Pages for a live demo

Source:

https://help.github.com/articles/creating-project-pages-manually/

http://lea.verou.me/2011/10/easily-keep-gh-pages-in-sync-with-master/

To create a Github Pages presence for your repo:

git checkout --orphan gh-pages
git merge master
git push origin gh-pages
git checkout master

The demo will be visible at username.github.io/reponame

To get the demo up-to-date with the master branch:

git checkout gh-pages
git merge master
git push origin gh-pages
git checkout master

Networking

List processes and the ports they’re listening on:

sudo netstat -tulpn

Or:

sudo netstat -an | less

List iptables rules:

sudo iptables -L -n

postgresql

.pgpass file

Linux: ~/.pgpass Windows: %APPDATA%/postgresql/pgpass.conf

The file should contain lines of the following format:

hostname:port:database:username:password

Example:

localhost:*:*:postgres:postgres

pg_dump

pg_dump --username=MYUSERNAME --file=MYDUMPFILE --format=custom DBNAME

pg_restore --username=MYUSERNAME --clean --dbname=DBNAME MYDUMPFILE

Google Test

Filter tests at compile-time

int main(int argc, char **argv)
{
  ::testing::GTEST_FLAG(filter) = "testSuiteName.testName";
  ::testing::InitGoogleTest(&argc, argv);
  RUN_ALL_TESTS();
}

This is equivalent to the run-time argument: --gtest_filter=testSuiteName.testName

Void Linux

Package management

xbps

Install a package (clang as an example):

sudo xbps-install -Su clang

Remove a package:

sudo xbps-remove clang

Check if a package is installed:

xbps-query -l | grep clang

Do a system update:

sudo xbps-install -u xbps && sudo xbps-install -Su

Clean up xbps cache, orphaned packages and old kernels:

sudo xbps-remove -yO
sudo xbps-remove -yo
sudo vkpurge rm all

xtools

Find the package to which the given file belongs:

xlocate -F /usr/share/nvim/runtime/indent.vim

List all packages that were manually installed:

xpkg -m

runit

TODO