ARCH

downgrade pkg

- if previously intstalled:
    -pacman -U /var/cache/pacman/pkg/old-pkg-version
- if not previously installed:
    - pacman -U https://archive.archlinux.org/packages/{some_letter}/some_pkg_name.tar.gz
- to temporarily ignore updates to a pkg that has been downgraded, add pkg to IgnorePkg section of /etc/pacman.conf
- if can't update b/c of pacman, run:
    - pacman-key --refresh-keys

view dep tree

- pactree

Audio

if volume levels keep resetting to 100% on each new song / video, add this line to /etc/pulse/daemon.conf flat-volumes = no
for refs: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=837637 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=837637
To find the duration of all audio files in a directory,use this command:
- soxi -D /path/to/files/* | awk 'a+=$1; END{print a}'
  
  ALSA / PulseAudio / Debian / Sound / Audio
Was having issues getting sound to play on Debian10 (buster)
Fixed with 'sudo alsactl init'
- alsactl -h / shows commands
- help screen showed that alsactl init returns driver to a default state
  
  AWS
  
  enabling https on EC2 Amazon Linux AMI
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/SSL-on-amazon-linux-2.html
- important: need to install mod24_ssl, not mod_ssl
- [ec2-user ~]$ cd /etc/pki/tls/certs sudo ./make-dummy-cert localhost.crt
- in /etc/httpd/conf.d/ssl.conf, comment out SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
- restart httpd sudo /etc/init.d/httpd restart

enable theme changes/updates on wordpress

https://stackoverflow.com/questions/8686125/update-wordpress-theme-on-ec2 sudo chown -R apache:ec2-user path/to/wordpress or sudo chown -R apache:apache path/to/wordpress

Lambda

Creating a Lambda function (with cli IAM role creation)

first, create trust-policy.json
second, create role
- aws iam create-role --role-name {some role name} --assume-role-policy-document file://trust-policy.json
third, attach permissions
- aws iam attach-role-policy --role-name {some role name} --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

Viewing logs from CLI

aws logs commands:
- combined command, to get most recent log stream for a log group:
  - aws logs describe-log-streams --log-group-name /aws/lambda/{fn name} --query 'logStreams[*].logStreamName' --max-items 1 --order-by LastEventTime --descending | awk -F'"' '$0=$2' | xargs aws logs get-log-events --log-group-name /aws/lambda/{fn_name } --log-stream-name | jq
- breakdown:
  - specify log group name based on fn name
  - query for 1 item, sorted by most recent
  - take val between two ""
  - pass name to xargs to get-log-events
  - jq to format json
- commands:
  - describe-log-groups
  - describe-log-streams --{log group name}
  - get-log-events --{log group name} -{log stream name}
    
    Run/invoke lambda function from CLI
aws lambda invoke --invocation-type RequestResponse --function-name {fn_name} --region ca-central-1 --cli-binary-format raw-in-base64-out --payload fileb:///code/{fn_name}/payload.json response.json
NOTE: running through a docker container will fail silently on AWS side; hash returned is just the docker id

deleting s3 buckets that have had improper policies attached to them
need to use use the aws cli to run 's3api delete-bucket-policy --bucket {bucket name}'
- can't use aws console, also can't delete bucket before deleting policy
need to use access keys of root account
- log in as root acct, generate new pair of access/secret access keys, use it to configure aws-cli in docker, delete key pair, re-config the image to use iam user creds,
- see steps below to configure/run docker aws-cli
adapting example below, command will be:
- (first run config with root creds)
- docker run --rm -v $HOME/.aws:/root/.aws amazon/aws-cli s3api delete-bucket-policy --bucket {bucket name}
  
  uploading cors configurations
- the xml syntax appears to be deprecated? Though I didn't see this mentioned anywhere.
- using the cli put-bucket-cors command solved the issue
- sudo docker run --rm -tiv $HOME/.aws:/root/.aws amazon/aws-cli s3api put-bucket-cors --bucket {bucket name} --cors-configuration file:///root/.aws/{config file name}.json
  - note the triple slash after file
  - I think 'file://' is needed to indicate a fileread, rather than reading a string from stdin

CALCURSE

to move date of appt:

-specify date as month/day (e.g., 1/1 for jan 1)

COMPTON

manually restart:

- pkill compton && compton --config ~/.config/compton.conf -bc

CMUS

remove cached metadata (e.g., after running id3convert -s */)

- :update-cache
- can use -f flag if not co-operating

repeat current song

- ^C

DJANGO

commands

create a new project

django-admin startproject {proj name}

create a new app
python manage.py startapp {app name}

start the development webserver
python manage.py runserver

DOCKER

running aws cli with credentials
#thanks to https://github.com/mikesir87/aws-cli-docker
- generate config and credentials files
  - docker run --rm -tiv $HOME/.aws:/root/.aws amazon/aws-cli configure
- run container with those files
  - docker run --rm -v $HOME/.aws:/root/.aws amazon/aws-cli describe instances
    
    stop and delete all containers
sudo docker stop $(sudo docker ps -a -q)
sudo docker rm $(sudo docker ps -a -q)

detach from running container

- ^P ^Q

clean up / remove dangling images

- docker prune  (prune -a; for more deletion)
- WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all dangling images
  - all dangling build cache

    -
    - or (according to my understanding of
      http://www.projectatomic.io/blog/2015/07/what-are-docker-none-none-images/),
      a dangling image is an intermediate image that is no longer the parent
      of any child image.  e.g., if you build hello-world image with fedora,
      and then later the fedora image gets updated, the intermediate OLD
      fedora layer for the hello world image no longer points to any
      child/final image.  I think...
- sudo docker rmi $(sudo docker images -a --filter=dangling=true -q)
    - where dangling = you've created a new build of an image, but it wasn't named
    - see: https://stackoverflow.com/questions/45142528/docker-what-is-a-dangling-image-and-what-is-an-unused-image)
    - is this deprecated by --remove-orphans?
    - note: docker docs refer to these as both orphans and dangling
    - https://forums.docker.com/t/how-do-i-remove-orphaned-images/1172

run container with interactive shell (first create if needed)

docker run -i -t {image name} /bin/bash
    // i - interactive
    // t - allocate a psuedo tty (from docker docs, not sure whta this means)

Container and Image Management

Containers

Lifecyle

create - creates a container but does not start it
rename - allows the container to be renamed
run - creates and starts a container in one operation
rm - deletes a container
    - shortcut to remove al docker containers:
        - sudo docker rm $(sudo docker ps -a -q)
update - updates a container's resource limits

Starting and Stopping

start - starts a container so it is running
stop - stops a running container
restart - stops and starts a container
pause - pauses a running container, "freezing" it in place
unpause - will unpause a running container
wait - blocks until running container stops
kill - sends a SIGKILL to a running container
attach - will connect to a running container

Info

ps - shows running containers
logs - gets logs from container
inspect - looks at all the info on a container
events - gets events from container
port - shows public facing port of container
top - shows running processes in container
stats - shows containers' resource usage statistics
diff - shows changed files in the container's FS

Images

Lifecycle

images - shows all images
import - creates an image from a tarball
build - creates image from Dockerfile
    -t - tag iamge
    -f - specify dockerfile
    - e.g., docker build -t ThisWillBeTheImageTag -f abnormDockerFileName .
commit - creates image from a container
rmi - removes an image.
load - loads an image from a tar archive
save - saves an image to a tar archive

Info

history - shows history of an image
tag - tags an image to a name (local or registry)

FLASH

- can use lightspark, available as standalone and broswer extensoin

GENTOO

Portage tips

* --noreplace stops re-installing of default packages
* --jobs=X to run parallel installs
* for full system/world update: 
    * sudo emerge --update --changed-use --deep --ask --with-bdeps=y @world

GIMP

Highlight a section of an image

Select a brush
choose "Darken Only" mode.
Set size and color of brush
Click start of area to highlight. Hold shift. Click end of area.

GIT

delete files from history (specifically large files)

using bfg - recommended for removing large files

https://rtyley.github.io/bfg-repo-cleaner/
- download file
java -jar ~/source_packages/bfg-1.13.1.jar --strip-blobs-bigger-than 40M repo_name.git

using filter-brach

git filter-branch --index-filter 'git rm -r --cached --ignore-unmatch unwanted_file_or_dir' --prune-empty

view files on a different branch without switching branches

git show branch:filepath/filename

- e.g., git show master:README.md

to sync a forked, local repo, can use the rebase command, which will avoid the ugly merge commit added when doing a normal pull.

- git pull --rebase <remote name> <branch name>

rename a local branch

- git branch -m <oldname> <newname>

fix merge conflicts with binary files:

- can choose local or remote with:
- git checkout --theirs path/to/file.png, for remote
- or --ours, for local

Modify last, unpushed commit:

- first, make needed changes, stage them with "git add file2" then run
- git commit --amend

unstage added, but uncommitted, changes:

- git reset

abort failed merge (e.g., pulling from wrong branch, now merge conflicts)

- git merge --abort

use vimdiff for git difftool

- git config diff.tool vimdiff
- also: Gdiffsplit (from fugitive)
- once split, :diffget and :diffput make editing a diff really easy

grep / search history of files (source code)

git grep {regex to search} $(git rev-list --all)

GPG

reset gpg-connect-agent / clear stored passwords

- echo RELOADAGENT | gpg-connect-agent

I3 (i3wm, window manager )

Move a window to a named workspace:

(mod+d to bring up dmenu) - i3-msg move container to workspace number 1 firefox

open a named workspace
(mod+d to bring up dmenu) - i3-msg workspace number 1 firefox

Javascript

Run Prettier for code formatting, w/in vim

- :Prettier

Jupyter and jupyterlab

autoreload modules:

- %load_ext autoreload
- %autoreload 2

- the first command 'loads extension' autoreload, which is disabled by default
- '2' means reload everything; 0 means nothing; 1 is only for modules loaded via %aimport
- see: https://switowski.com/blog/ipython-autoreload

install vim keybindings:

- jupyter labextension install @axlair/jupyterlab_vim
- using this specific repo/version because the newest (2020-09-30) version
  of jupyterlab doesn't support newest version of the extension
    - see: https://github.com/jwkvam/jupyterlab-vim/issues/118

matplotlib integration

pip install ipympl pip install nodejs jupyter labextension install @jupyter-widgets/jupyterlab-manager jupyter labextension install jupyter-matplotlib

KVM / QEMU / virt-manager

to mount host dir and share files with guest
1. create dir to mount (e.g., /tmp/share) 2 Add shareable filesystem via virt-manager
  - Hardware (lightbulb) -> +Add Hardware -> Filesystem -> Driver=Default, Mode=Squashed, set source path and target path
2. mount shared dir in guest:
  - sudo mount -t 9p -o trans=virtio,version=9p2000.L /hostshare /tmp/hostshare
    
    LaTeX
3. cancel a compilation:
  - x

LibreOffice

Fix fonts and icons, when installing on debian based system, by installing libreoffice-gtk3
- This helped a great deal with an i3-based install, anyway

LINUX

install .deb package

sudo dpkg -i filename.deb

OCR (extract text from image)

use tesseract-ocr
tesseract-ocr input.png output.txt

toggle caps lock when xmm applied recklessly... locking CAPS LOCK on

xdotool key Caps_Lock

Webcam/sound Recording tips
record webcam embedded in screen:
- mplayer tv:// -tv driver=v4l2:width=320:height=240 -vo xv
- mplay has been easier to use. Can also use ffmpeg:
- ffplay -f v4l2 /dev/video0
eliminate static from mic when recording:
- sudo bash ~/noise_cancellation_script.sh && pulseaudio -k
- noise_cancellation_script.sh (see file for attribution): sudo cp /etc/pulse/default.pa /etc/pulse/default.pa.bak sudo cat <> /etc/pulse/default.pa load-module module-echo-cancel source_name=noechosource sink_name=noechosink set-default-source noechosource set-default-sink noechosink EOT

toggle between ttys (e.g., between term and xorg):

- ctrl+atl+{f1-f7}
- OR  alt+left or alt+right
    - this latter works to get back to a running xorg session

installing with dpkg when dependencies missing

if running 'sudo dpkg -i {filename}.deb' and hitting a missing dependency error, do the following to use 'fix-missing' functionality:
- # apt-get update --fix-missing
- sudo apt-get update -f
  - long-form (apt-get update --fix-broken)
    
    customize desktop and icons (themes)
lxappearance is an easy gui tool

determine file type in terminal

file -i {filename}

set default web browser (particularly in Debian sytems)
- xdg-settings set default-web-browser firefox-esr.desktop
  
  set default applications
xdg-mime --help
- not optimal??
to set default file manager:
- edit ~/.config/mimeapps.list
NOTE: firefox cannot launch an external application like thunar/nautilus if it's running under firejail

crontab and mysqldump gotcha - escaping percent sign
- \% for dates and such
  
  printing (CUPS - common unix print system)
- start daemon on openRC
  - rc-service cupsd start
- http interface
  - http://localhost:631/
- if not detecting usb printer, could be permissions/ownership issue (see https://wiki.gentoo.org/wiki/Printing#Configuration)
  - lsusb will show bus and device
    - e.g., Bus 001 Device 004: ID 03f0:ce11 Hewlett-Packard
  - the character device for this will be at:
    - ls /dev/bus/usb/001/004
  - fix ownership and permissions
    - # chgrp lp /dev/bus/usb/001/004
    - # chmod 660 /dev/bus/usb/001/004
  - printer should appear now
- problem with printing pdfs with forms in evince (apparently in okular too)
  - one workaround is to open the pdf in firefox, print to pdf, then print from evince (ugh; maybe can compile firefox with print support on gentoo? )

full system backup (from linux.com/learn/full-metal-backup-using-dd-command)

- backup to a compressed image file:
    - sudo dd if=/dev/sda conv=sync,noerror status=progress, bs=64k | gzip -c > /PATH/TO/DRIVE/backup_image.img.gz
- restore from image file:
    - gunzip -c /PATH/TO/DRIVE/backup_image.img.gz | dd of=/dev/sda

home dir backup

- create it:
    - nav to location where backup will store, eg /mnt/ultrabay_hdd,
      (so as not to cause tar failure/warning)
    - tar -cz /home/km | gpg -c -o home_dir_backup_DATE.tgz.gpg
- restore it:
    - gpg -d home_dir_backup_DATE.tgz.gpg | tar -xz

view csv files on command line

use column

column -s, -t < {filename}

use csvtool

email backup
- nav to where backup will be stored (so as not to cause tar failure/warning)
- tar -cz /home/km/email /home/km/mail_configs | gpg -c -o /mnt/dock_hdd/em_bk_190218.tgz.gpg

reset failed login count (to reenable acct after failed logins)

- faillog -r -u <user>

logfiles

- /var/log is main dir
- /var/log/syslog is main file
- use grc, the generic colouriser, to colourise log files, e.g.:
    - sudo grc less /var/log/syslog

capture screenshot

- imagemagick / ImageMagick 
- provides the 'import' function:
    - `import test.jpg` - click for window, drag for selection
    - `import -window root screenshot.png` - full desktop, multiple monitors

find out which system you are on

- lsb_release -a
- cat /etc/issue.logo

kernel options format

- tips/portage output with the following appearance are often kernel options:
    - CONFIG_SNG_HDA_PREALLOC_SIZE=64

generate random password from terminal/CLI

- openssl rand -base64 14

reset terminal

- if terminal goes bananas, with a bunch of crazy characters, can use the
    'reset' command to clear screen and reload.  Sometimes helps on headless
    machines.

unfreeze a terminal (when you accidentally press Ctrl-S)

- Ctrl-Q

video capture & webcam, kernel modules/setup

- great information at https://nlug.ml1.co.uk/2013/02/gentoo-kernel-3-7-9-webcams-v4l-uvc-video-kernel-config/3965
- modules needed (for logitech c270, uvc-based cam):
    - CONFIG_MEDIA_SUPPORT
    - CONFIG_MEDIA_CAMERA_SUPPORT
    - CONFIG_MEDIA_USB_SUPPORT
    - CONFIG_USB_VIDEO_CLASS

wifi restart (wifi issues)

- restart service
    - disconnect from connection
    - # systecmtl stop networking
    - # rmmod brcmfmac
    - # modprobe brcmfmac
    - # systemctl start networking.service

- check dmesg logs for messages
- remove/re-add kernel module - # rmmod brcmfmac & # modprobe brcmfmac

add user to group (e.g., sudo group)

- usermod -aG sudo km

METADATA

mp3 files

strip with id3lib
$ id3convert -s {filename}

MUTT

mass clearing flags (e.g., O for Old)
tag with 'T'
l to filter (i.e., set tag pattern)
- ~O matches all old messages
';' performs action on all tagged messages
W clears flag (w sets)
enter flag to clear (here, O)

example: inbox full of read messages, just want to archive: commands: T ~O ; W O

taken from
- https://brianbuccola.com/how-to-mark-all-emails-as-read-in-mutt/
  
  cancel prompt
- ctrl-g
  
  view other mailboxes
- y
  
  sync (i.e., actually delete marked)
- $
  
  tag all messages matching a pattern
- T
  
  show only messages matching a pattern
- l
  
  apply next function to all tagged messages
- ;
  
  clear flag
- W (uppercase clears flags)
- w (lowercase is to add flag)
  
  resend a message that was bounced
- Esc-e
  
  Detach a file (i.e., delete an attachment)
  - D
    
    move message to another mailbox
  - s (for save)
  - ? to choose mailbox
    
    redraw screen (clear artifacts)
  - Ctrl-t (function is redraw-screen in index)
    
    MYSQL
    
    Reset a lost root pw
  - shutdown db service, start in safe mode, connect as root, change pw, restart $ sudo systemctl stop mariadb $ sudo mysqld_safe --skip-grant-tables --skip-networking & $ mysql -u root
    
    mysql> use mysql; mysql> UPDATE user SET password=PASSWORD('YourPasswordHere') WHERE User='root' AND Host = 'localhost'; mysql> flush privileges; mysql> quit
    
    (alternate syntax for update command) mysql> update user set authentication_string=password('NEWPASSWORD') where user='root';

cheatsheet.md 40 KB Geçmiş Ham

ARCH

downgrade pkg

view dep tree

Audio

ALSA / PulseAudio / Debian / Sound / Audio

AWS

enabling https on EC2 Amazon Linux AMI

enable theme changes/updates on wordpress

Lambda

Creating a Lambda function (with cli IAM role creation)

Viewing logs from CLI

Run/invoke lambda function from CLI

deleting s3 buckets that have had improper policies attached to them

uploading cors configurations

CALCURSE

to move date of appt:

COMPTON

manually restart:

CMUS

remove cached metadata (e.g., after running id3convert -s */)

repeat current song

DJANGO

commands

create a new project

create a new app

start the development webserver

DOCKER

running aws cli with credentials

stop and delete all containers

detach from running container

clean up / remove dangling images

run container with interactive shell (first create if needed)

Container and Image Management

Containers

Lifecyle

Starting and Stopping

Info

Images

Lifecycle

Info

FLASH

GENTOO

Portage tips

GIMP

Highlight a section of an image

GIT

delete files from history (specifically large files)

using bfg - recommended for removing large files

using filter-brach

view files on a different branch without switching branches

to sync a forked, local repo, can use the rebase command, which will avoid the ugly merge commit added when doing a normal pull.

rename a local branch

fix merge conflicts with binary files:

Modify last, unpushed commit:

unstage added, but uncommitted, changes:

abort failed merge (e.g., pulling from wrong branch, now merge conflicts)

use vimdiff for git difftool

grep / search history of files (source code)

GPG

reset gpg-connect-agent / clear stored passwords

I3 (i3wm, window manager )

Move a window to a named workspace:

open a named workspace

Javascript

Run Prettier for code formatting, w/in vim

Jupyter and jupyterlab

autoreload modules:

install vim keybindings:

matplotlib integration

KVM / QEMU / virt-manager

LaTeX

LibreOffice

LINUX

install .deb package

OCR (extract text from image)

toggle caps lock when xmm applied recklessly... locking CAPS LOCK on

Webcam/sound Recording tips

toggle between ttys (e.g., between term and xorg):

installing with dpkg when dependencies missing

cheatsheet.md 40 KB

Geçmiş Ham