Change slogan

cirosantilli · cirosantilli · commit d4c6e120174c · 2016-05-30T19:50:25.000+02:00
diff --git a/README.md b/README.md
@@ -1,6 +1,6 @@
 # Linux Cheat ![logo](logo.jpg)
 
-Linux tutorials and cheatsheets. Minimal examples. Mostly user-land.
+Linux tutorials and cheatsheets. Minimal examples. Mostly user-land CLI utilities.
 
 Includes Linux concepts and utilities that work on Linux, not necessarily in the LSB. So this is a big dump of useful things, and when something gets big / useful enough, I split to another repository.
 
@@ -60,6 +60,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1.  [mountall](mountall.md)
     1.  [pathchk](pathchk.md)
     1.  [rsync](rsync.md)
+    1.  [rm](rm.md)
     1.  [sync](sync.md)
     1.  [swap partition](swap-partition.md)
     1.  [tune2fs](tune2fs.md)
@@ -130,7 +131,6 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [echo](echo.sh)
     1. [column](column.md)
     1. [cut](cut.sh)
-    1. [Eclipse](eclipse.md)
     1. [expand](expand.md)
     1. [fold](fold.md)
     1. [paste](paste.md)
@@ -142,6 +142,10 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [uniq](uniq.md)
     1. [uuencode](uuencode.md), `uudecode`
     1. [wc](wc.md)
+1.  IDEs
+    1. [Eclipse](eclipse.md)
+    1. [Code::Blocks](codeblocks.md)
+    1. [KDevelop](kdevelop.md)
 1.  Binary data viewers
     1. [hd](hd.md)
     1. [hexdump](hexdump.md)
@@ -169,6 +173,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
         1.  [pmap](ps.md)
         1.  [ps](ps.md)
         1.  [top](top.md)
+        1.  [watch](watch.md)
     1.  psmisc
         1.  [killall](killall.md)
     1.  [Shebang](shebang/)
@@ -220,6 +225,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
                 1. [HandBrake](handbrake.md)
         1.  Trivia
             1. [MPEG LA](mpeg-la.md)
+        1.  [VLC](vlc.md)
     1.  [Camera](camera.md)
         1.  [Video4Linux](video4linux.md)
 1.  File sharing
@@ -315,7 +321,7 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1.  [Statistics](statistics.md)
 1.  Packages
     1. [util-linux](util-linux.md)
-1.  Simulation
+1.  [Physics](physics.md)
     1. [gazebo](gazebo.md)
 1.  Misc
     1.  [BusyBox](busybox.md)
diff --git a/alternatives.md b/alternatives.md
@@ -14,8 +14,9 @@ Strict real time:
 
 - <https://en.wikipedia.org/wiki/QNX>, proprietary, micro-kernel, bought by BlackBerry.
 - <https://en.wikipedia.org/wiki/VxWorks>, proprietary
-- <https://en.wikipedia.org/wiki/ECos> GPL, started by Cygnus, discontinued by Red Hat, copyright later transfered to the FSF.
+- <https://en.wikipedia.org/wiki/ECos> GPL, started by Cygnus, discontinued by Red Hat, copyright later transferred to the FSF.
 - <https://en.wikipedia.org/wiki/FreeRTOS>
+- <https://en.wikipedia.org/wiki/Micro-Controller_Operating_Systems> proprietary with source available
 
 Dedicated OSes / firmware:
 
diff --git a/audio/README.md b/audio/README.md
@@ -188,7 +188,7 @@ Rip from DVD:
 
 Automatically finds right configurations on most systems.
 
-Creates dir in cur dir and saves rip out as `.ogg` in it.
+Creates dir in cur dir and saves rip out as `.ogg` (Vorbis) in it.
 
 ## Synthesis
 
diff --git a/codeblocks.md b/codeblocks.md
@@ -4,6 +4,8 @@ Tested with: 13.12 Ubuntu 14.04
 
 <http://wiki.codeblocks.org/index.php?title=Keyboard_Shortcuts>
 
+Not recommended. Crashes a lot.
+
 ## Getting started
 
 ### Import projects
@@ -16,6 +18,8 @@ Tested with: 13.12 Ubuntu 14.04
 
 Not possible
 
+#### CMake
+
 ### Must have settings
 
 Open default workspace at startup:
@@ -26,6 +30,12 @@ Open default workspace at startup:
 
 Big as in GCC big.
 
+## Jump to declaration
+
+Ctrl + Shift + .
+
+No mouse shortcut??
+
 ## Bibliography
 
 <http://wiki.codeblocks.org/index.php?title=Keyboard_Shortcuts>
diff --git a/eclipse.md b/eclipse.md
@@ -364,6 +364,10 @@ HTML, JavaScript, PHP: <http://download.eclipse.org/webtools/repository/indigo/>
 
 #### CDT
 
+#### C++
+
+Hard to get working...
+
 C and C++: <http://download.eclipse.org/tools/cdt/releases/indigo/>
 
 For large projects, make sure that you add more memory to the VM at `Eclipse.ini` or the indexing hangs: <http://stackoverflow.com/questions/9565125/whats-the-recommended-eclipse-cdt-configuration-for-big-c-project-indexer-ta>
diff --git a/ffmpeg.md b/ffmpeg.md
@@ -10,6 +10,14 @@ List codecs: <http://stackoverflow.com/questions/3377300/what-are-all-codecs-sup
 
 ## Extract raw streams
 
+### VP9
+
+Freedom!
+
+    ffmpeg -framerate 4 -pattern_type glob -i '*.jpeg' -c:v vp9 out.webm
+
+TODO: quality is bad.
+
 ### H264
 
 - <http://stackoverflow.com/questions/10380045/is-there-any-easy-way-to-extract-h-264-raw-stream-in-annexb-format>
@@ -78,6 +86,23 @@ where `I`, `B`, and `P` are defined at: <https://en.wikipedia.org/wiki/Video_com
 
 From there on, Bash it up.
 
+## Images to video
+
+- <http://superuser.com/questions/624567/ffmpeg-create-a-video-from-images>
+- <http://askubuntu.com/questions/380199/converting-images-into-video>
+- <http://stackoverflow.com/questions/16315192/avconv-make-a-video-from-a-subset-on-images>
+- <https://trac.ffmpeg.org/wiki/Create%20a%20video%20slideshow%20from%20images>
+
+Just works:
+
+    ffmpeg -framerate 4 -pattern_type glob -i '*.jpg' -c:v libx264 out.mp4
+
+### Smooth transitions
+
+- <http://stackoverflow.com/questions/7565962/ffmpeg-fade-effects-between-frames>
+- <http://superuser.com/questions/778762/crossfade-between-2-videos-using-ffmpeg>
+- <http://superuser.com/questions/223678/how-to-convert-single-images-into-a-video-with-blending-transition>
+
 ## ffplay
 
 Minimalistic video preview tool.
diff --git a/imagemagick.md b/imagemagick.md
@@ -171,7 +171,7 @@ The first `-depth 8`, specifies it for the input, and the second for the output.
 
 #### Depths that are not multiple of 8
 
-TODO: what happens when depth < 8? http://stackoverflow.com/questions/10155092/how-do-i-convert-image-to-2-bit-per-pixel ImageMagick packs multiple bits per byte since it is not possible to address bits, but I don't understand exactly how. Specially, because it depends on the dimensions! E.g.;
+TODO: what happens when depth less than 8? http://stackoverflow.com/questions/10155092/how-do-i-convert-image-to-2-bit-per-pixel ImageMagick packs multiple bits per byte since it is not possible to address bits, but I don't understand exactly how. Specially, because it depends on the dimensions! E.g.;
 
     printf "%10s" | sed 's/ /\xFF\x00/g' > f.gray
     convert -depth 8 -size 1x20 f.gray -depth 2 g.gray
@@ -338,4 +338,6 @@ Checkerboard:
     printf "%1002001s" | sed 's/ /\xFF\x00/g' > f.gray
     convert -depth 8 -size 1001x2002 f.gray f.png
 
+## Trivia
 
+- http://arstechnica.com/security/2016/05/exploits-gone-wild-hackers-target-critical-image-processing-bug/
diff --git a/kdevelop.md b/kdevelop.md
@@ -0,0 +1,65 @@
+# KDevelop
+
+Tested on 4.7.3.
+
+Very good first impression for C++ CMake. Worked really fast, easy to find how to do the basic things that I need.
+
+C / C++ focused, but other languages also supported: <http://developer.kde.org/~larrosa/visualtutorial/chapter02.html>
+
+## Settings
+
+- Vi input mode: Settings > Editing > Vi input mode > Use
+
+## Navigate souce
+
+- Import existing source: File > Import > CMake. Done. Just works!
+- Jump to definition: Ctrl + click.
+- View class hierarchy and method layout: Right click on class name > Find in class browser
+- Jump to previous location: Meta + Left (oh now, meta usage inside non window manager program...)
+- Find uses: Right click > Find uses. Shows either calls, definitions or declarations.
+- Next / previous tab keyboard shortcut: http://stackoverflow.com/questions/37050415/how-to-move-to-the-next-previous-right-left-file-tab-on-kdevelop-with-a-ke
+- Ctrl + Alt + B: toggle breakpoint on current line
+- Ctrl + Alt + O, type filename / symbol name: autocomplete jump to file that matches file / symbol
+
+## TODO
+
+- find uses of macro
+- send stdin to running executable from console
+
+## Build and run
+
+- F8: compile
+- Shift + F9: run
+
+## Debug
+
+First you must compile with debug symbols.
+
+With CMake: <http://stackoverflow.com/questions/24322956/kdevelop-steps-and-breakpoints-not-working>
+
+CMake manage multiple build configurations: <http://stackoverflow.com/questions/15064715/kdevelop-with-cmake-project-how-to-manage-debug-and-release-builds>
+
+- F9: run in debugger mode. TODO: hitting it multiple times just stops the previous one and starts a new one?
+- F10: GDB next
+- F11: GDB step
+- F12: GDB finish
+- Continue: no default keyboard shortcut! I set it to Shift + F10.
+
+Watch variable: hover it, Watch this. Could not find on right click...
+
+Find the actual derived type of a pointer to a base class: TODO. For GDB only: <http://stackoverflow.com/questions/8528979/how-to-determine-if-an-object-is-an-instance-of-certain-derived-c-class-from-a>
+
+Current UI for the debug pane is bad:
+
+- jump to line of breakpoint on editor: <https://forum.kde.org/viewtopic.php?f=218&t=125905#p338944> No mouse method or visible indication!
+- cannot select multiple breakpoints at once to delete them
+
+## Bibliography
+
+Documentation: https://docs.kde.org/trunk5/en/extragear-kdevelop/kdevelop/index.html
+
+### Reviews
+
+Positive:
+
+- <http://www.gnurou.org/code/kdevelop-kernel>
diff --git a/parallel.md b/parallel.md
@@ -6,7 +6,7 @@ GNU.
 
 Run `echo` 100 times in parallel:
 
-    seq 100 | parallel echo {}
+    seq 100 | parallel echo '{}'
 
 ## halt
 
diff --git a/physics.md b/physics.md
@@ -0,0 +1,6 @@
+# Physics
+
+Finite element:
+
+- <https://www.quora.com/What-is-the-best-open-source-Finite-Element-Method-software>
+- <http://feacompare.com/>
diff --git a/proc-filesystem.md b/proc-filesystem.md
@@ -210,7 +210,7 @@ The names come from several sources: some are vendor specific like Intel and AMD
 
 Contains kernel parameters.
 
-Those can also be modified with `sysctl`.
+Those can also be modified with `sysctl`. Options will be documented there.
 
 ## /proc/uptime
 
diff --git a/ramfs.md b/ramfs.md
@@ -26,7 +26,7 @@ Create a tmpfs:
 Create a ramfs:
 
     sudo mkdir -p /mnt/ramfs
-    sudo mount -t ramfs -o size=100m ramfs /mnt/ramfs
+    sudo mount -t ramfs -o size=300m ramfs /mnt/ramfs
 
 Undo with:
 
diff --git a/rm.md b/rm.md
@@ -0,0 +1,14 @@
+# rm
+
+## Speed up
+
+Deleting files is **way** slower than creating them.
+
+I wonder if the creation order matters: if files are in a SHA pattern it's horrible!
+
+- <http://askubuntu.com/questions/114969/is-there-any-faster-way-to-remove-a-directory-than-rm-rf>
+- <http://serverfault.com/questions/128012/how-to-make-rm-faster-on-ext3-linux>
+- <http://serverfault.com/questions/183821/rm-on-a-directory-with-millions-of-files/328305#328305>
+- <http://stackoverflow.com/questions/1795370/unix-fast-remove-directory-for-cleaning-up-daily-builds>
+- <http://superuser.com/questions/680119/deleting-millions-of-files>
+- <http://unix.stackexchange.com/questions/37329/efficiently-delete-large-directory-containing-thousands-of-files>
diff --git a/sysctl.md b/sysctl.md
@@ -72,3 +72,7 @@ All files in the `.d` get sourced.
 The effective hostname.
 
 Normally taken from `/etc/hostname` at startup.
+
+## swappiness
+
+<http://askubuntu.com/questions/103915/how-do-i-configure-swappiness>
diff --git a/ulimit.md b/ulimit.md
@@ -111,6 +111,11 @@ Linux deals well with CPU limits since CPU usage rotates according to nice, but
 
 The timeout tool aims to limit CPU and RAM for the children as well as parent: <https://github.com/pshved/timeout>
 
+### CPU usage
+
+- <http://stackoverflow.com/questions/386945/limiting-certain-processes-to-cpu-linux>
+- <http://unix.stackexchange.com/questions/151883/limiting-processes-to-not-exceed-more-than-10-of-cpu-usage>
+
 ## Per user limits
 
 ### PAM
diff --git a/unicode.md b/unicode.md
@@ -64,6 +64,12 @@ Therefore:
 
     There is even a wiki with famous strategies: <http://en.wikipedia.org/wiki/Transformation_of_text>
 
+-   Full width characters <https://en.wikipedia.org/wiki/Halfwidth_and_fullwidth_forms>
+
+    Twice as wide as normal ASCII. Used in Asian languages like Chinese where most characters are also 2x wider than normal ASCII.
+
+        ＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯ
+
 ### Whitespace
 
 Unicode NBSP variants: <http://en.wikipedia.org/wiki/Non-breaking_space#Width_variations>
diff --git a/virtualization.md b/virtualization.md
@@ -83,17 +83,17 @@ Important niche of application for VMs include:
 
 ## Emulation vs virtualization
 
--   emulation vs virtualization: <http://stackoverflow.com/questions/6044978/full-emulation-vs-full-virtualization>
+<http://stackoverflow.com/questions/6044978/full-emulation-vs-full-virtualization>
 
-    Emulation is usually said to be software only, while virtualization uses hardware support, making it way faster.
+Emulation is usually said to be software only, while virtualization uses hardware support, making it way faster.
 
-    The x86 family has hardware features that improve performance and may be even required for certain virtualizations.
+The x86 family has hardware features that improve performance and may be even required for certain virtualizations.
 
-    Those features can be turned on or off by the BIOS, and in many modern systems they come turned off by default.
+Those features can be turned on or off by the BIOS, and in many modern systems they come turned off by default.
 
-    If you plan on using virtualization, the first thing you should do is to enable such features by going into the BIOS config (first screen shown at computer startup), and looking for a virtualization section.
+If you plan on using virtualization, the first thing you should do is to enable such features by going into the BIOS config (first screen shown at computer startup), and looking for a virtualization section.
 
--   Docker: <https://github.com/dotcloud/docker>
+Docker: <https://github.com/dotcloud/docker>
 
 ### Hypervisor
 
@@ -104,6 +104,14 @@ TODO vs virtualization?
 
 KVM: hard to say.
 
+## Cycle accurate simulation
+
+Simulates speed well.
+
+Public simulators do not exist for closed source chips I know of.
+
+Likely because they would reveal too much internals and leak IP.
+
 ## File formats
 
 ### ovf
diff --git a/vlc.md b/vlc.md
@@ -0,0 +1,8 @@
+# VLC
+
+- `k`, `l`: move subtitles a bit forwards or backwards. Awesome!
+
+## Videos with small frame-rate
+
+- <https://forum.videolan.org/viewtopic.php?f=2&t=41347&p=442385#p442385>
+- <https://trac.videolan.org/vlc/ticket/214>
diff --git a/watch.md b/watch.md
@@ -0,0 +1,11 @@
+# watch
+
+    watch -n1 date
+
+Multiple commands:
+
+    watch -n1 bash -c 'date;date'
+
+TODO multiple commands and `sudo`. Why does not work?
+
+    watch -n1 bash -c 'sudo ls'
diff --git a/wmctrl.md b/wmctrl.md
@@ -91,3 +91,9 @@ Many apps do that with CLI arguments, and you should prefer that method if avail
     wmctrl -xa gvim -b add,fullscreen
 
 TODO: when I hit `Alt + Tab`, the list of applications does not show anymore on Ubuntu 15.10...
+
+## Focus window opened by command
+
+Non-trivial of course because there is no simple bijection between windows and executables:
+
+<http://unix.stackexchange.com/questions/167379/set-focus-to-newly-open-window>
diff --git a/xargs.md b/xargs.md
