7yl4r / cheatsheets

:memo: my personal collection of cheatsheets

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• data viz catalogue

*nix

piping & redirection

# pipe stderr & stdin to file
echo texthere &> myfile.txt

# redirect STDERR (2) to STDOUT (1) from docker logs, pipe to grep regex
docker logs erddap 2>&1 | grep -E "WARN|ERR"

# tee to print and save log to file
cmd | tee filename.log

archives

common .tar.gz tarball

• tar -xvf archive.tar.gz : extract verbose filename

high-compression (xz)

• .xz compress: tar -cvJf file.tar.xz files/
• .xz extract: tar -xvf file.tar.xz

tar flag summary:

• -x extract
• -v verbose
• -f filename
• -c compress
• -J xz

http downloads

# download file
curl http://example.com --output my.file

rsync

Basic usage is usually -azvh:

    -a --archive
    -z --compress
    -v --verbose
    -h --human_readable

grep

search without -v and use regex -E:

grep -Ev "word1|word2" example.txt

Examples

# For directory merging. Keeps most-recently modified version of files. 
rsync -habviuzP $OLDLOC/ $NEWLOC`  

# Sending to a remote server (eg USF supercomputer CIRCE)
rsync -azvh *-M1BS-* [e-mail]:/work/t/tylarmurray/img/Jobos/

ssh

# generate new ssh id for your local user account
ssh-keygen -t ed25519 -C "[e-mail]"  # NOTE: use default names & no pw otherwise you may need to configure w/ ssh-agent

# install ssh key on a remote server
ssh-copy-id -i ~/.ssh/id_rsa.pub [e-mail]

networking

test connection to port

# use telnet
[root@seashell ~]# telnet 35.211.139.69 7070
Trying 35.211.139.69...
Connected to 35.211.139.69.
Escape character is '^]'.
^CConnection closed by foreign host.

# use netcat to test tcp
[root@seashell ~]# nc -z -v 35.211.139.69 7070
Connection to 35.211.139.69 7070 port [tcp/arcp] succeeded!

# use netcat to test udp
[root@seashell ~]# nc -z -v -u 35.211.139.69 7070
Connection to 35.211.139.69 7070 port [udp/arcp] succeeded!

disks

# view disk config
lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT

partition + format

# === partition
gdisk /dev/$DISK
# p : show partitions 
# n : new
#    p : primary
# w : write and exit

# === fs setup
/sbin/mkfs.ext4 /dev/$DISK  # create file system on new partition
mount /dev/$DISK /loc/to/mount/to`  # temp test mount
vi /etc/fstab  
# && and add a line like:
# /dev/$DISK  /loc/to/mount/to   ext4    defaults    0   0`

• fstab info

accounts

groupadd -g 4747 grpname

useradd -d /home/ty -u 4747 -g 4747 -G sudo,admin,common -e 2999-12-30 ty
useradd -M nohomeuser

# add user to a group
usermod -a -G grpname username

# delete user
userdel username

permissions

# set group permissions same as user
chmod -R g=u /location

# show permissions of full directory tree
namei -mo /home/user/dir/child/file

clipboard-to-files

# see possible targets
xclip -selection clipboard -t TARGETS -o
# example to create image from clipboard
xclip -selection clipboard -t image/png -o > /tmp/myimage.png

find

# exec
find . -exec grep chrome {} \;
# exec w/ pipe
find /path/to/jpgs -type f -exec sh -c 'jhead -v {} | grep 123' \;
# w/ xargs & command substitution
find ./content -type f -name 'DESCRIPTION' -print0 | \
    xargs -0 Rscript -e "devtools::install( \"$(sed -r 's|/[^/]+$||')\")"

Space-saving Tips

# inspect the size of files in a directory
du -sh ./my_directory/*

# search for big files (example shows >5G)
find ./ -type f -size +5G

# search for unused files (example unaccessed for >90 days)
find ./ -type f -atime +90

# find content-identical files of size >10MB
jdupes -r -S -X size-:10M ./my_dir/

FTP

lftp -c mirror ftp://ftp.nodc.noaa.gov/nodc/archive/arc0139/0190272/1.1/data/0-data/Sargassum_areal_coverage/
lftp [e-mail]:/3864_2019jul29> mirror --use-pget-n=4 .

Text Editing

# find & replace text
sed 's/word1/word2/g' input.file > output.file

vi

# delete all lines with given ending:
:g/_the_ending\.txt$/d

system info

# distro info
cat /etc/*elease

one-time setup stuff

# set my `history` cmd preferences:
echo 'export HISTTIMEFORMAT="%y-%m-%d %T "' >> ~/.bash_profile
echo 'export HISTCONTROL=ignoreboth:erasedups ' >> ~/.bash_profile
echo 'export HISTSIZE=100000 ' >> ~/.bash_profile
echo 'export HISTFILESIZE=10000000 ' >> ~/.bash_profile