Table of contents
A
adb
# get device mac address mac_addr mac secret mac_sec
adb shell idme print
# start adb shell as root
adb shell su
# reboot
adb reboot
# get properties
adb shell get-dynconf-value <property_name>
# sendText
adb shell sendText <text>
alias
alias sshp
# how to set ssh to not use proxy command?
alias sshp='ssh -o ProxyCommand=none'
B
bg
# ctrl + z to suspend a foreground job
bg %1 # resume job 1 in background
C
chmod
chmod 777 -R <dir> # set read write executable for directory by user, group, others
chmod a+rwx -R <dir> # same as above
chmod +x <file> # make file executable by anyone, +x, a+x, same as ugo+x
chown
sudo chown -R <user1> ./folder # recursively change owner to user1 for folder
D
date
date +%F # today's date 2018-04-21
date # Sat Apr 21 16:43:16 PDT 2018
date -r <epoch seconds> # example 1547927682
> date +%s # Current time seconds, mac
1544081888
> date -v -15M +%s # 15 minutes ago in seconds, mac
1544081034
> date -r 1544081034 # seconds to readable, mac
Thu Dec 6 09:23:54 IST 2018
> date +%s # Current time seconds, linux
1544082214
> date -d "15 mins ago" +%s # 15 minutes ago in seconds, linux
1544081345
> date -d @1544081345 # seconds to readable, linux
Thu Dec 6 07:29:05 UTC 2018
today=$(date +%Y/%m/%d) # today's date in format 2020/02/22
today=$(date) # Sat Feb 22 06:15:12 UTC 2020
date -d $today +%Y/%m/%d # reformat date
df
How to check disk space on the command line?
% df -h
# mac result
Filesystem Size Used Avail Capacity iused ifree %iused Mounted on
/dev/disk3s1s1 460Gi 10Gi 343Gi 3% 412k 3.6G 0% /
devfs 204Ki 204Ki 0Bi 100% 706 0 100% /dev
/dev/disk3s6 460Gi 20Ki 343Gi 1% 0 3.6G 0% /System/Volumes/VM
/dev/disk3s2 460Gi 6.4Gi 343Gi 2% 1.2k 3.6G 0% /System/Volumes/Preboot
/dev/disk3s4 460Gi 3.0Mi 343Gi 1% 53 3.6G 0% /System/Volumes/Update
/dev/disk1s2 500Mi 6.0Mi 483Mi 2% 1 4.9M 0% /System/Volumes/xarts
/dev/disk1s1 500Mi 5.6Mi 483Mi 2% 32 4.9M 0% /System/Volumes/iSCPreboot
/dev/disk1s3 500Mi 824Ki 483Mi 1% 74 4.9M 0% /System/Volumes/Hardware
/dev/disk3s5 460Gi 99Gi 343Gi 23% 1.4M 3.6G 0% /System/Volumes/Data
map auto_home 0Bi 0Bi 0Bi 100% 0 0 - /System/Volumes/Data/home
/dev/disk3s3 460Gi 986Mi 343Gi 1% 41 3.6G 0% /Volumes/Recovery
/dev/disk4s2 167Gi 2.7Gi 165Gi 2% 108k 4.3G 0% /Volumes/code
du
How to check disk space usage on the command line?
du -b <file> | cut -f1 # get file size in bytes
# list file and folder sizes in current directory
sudo du -sh * | sort -h -r
du -ahx . | sort -rh | head -5
du -hd 1 . # mac
F
fg
fg %4 # bring job 4 to foreground
find
# search text in gz zipped log
find . -name "*.gz" -exec zgrep -nI "text to search" {} +
G
Git
How to check a github repo size?
See stackoverflow reference.
We can check with GET /repos/:user/:repo with GitHub API.
You can access https://api.github.com/repos/<user_or_organization_name>/<repo_name> with a browser such as google chrome.
or use curl
How to Check the Summary (Changed Files) of the Last Commit?
git log -1 --stat # show basic info and all changes
git show -1 --summary # show basic info and created or removed files, does not include changed files
other commands
# rename branch
git branch -m <new_branch_name>
# view branch detailed info
git branch -vv
# set upstream
git branch -u <remote>/<branch_name>
# cherry pick remote commit
git fetch origin
git cherry-pick <commit hash>
# stash change for later
git stash save <useful message>
git stash show -p stash@{1}
git push <remote-name> <local-branch-name>:<remote-branch-name> # add -u to track remote branch with local branch, i.e. set as upstream
# delete remote branch
git push -d <remote_name> <branch_name>
git push origin --delete <branch_name>
# show last three tags
git tag -l | tail -3
# github ssh setup
https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent
git log --all --oneline --graph
# --decorate only applies to the head, --decorate=full example: commit 6b51db131e32e8fcaaa075e7d1134dbf9f7359ee (HEAD -> refs/heads/main, refs/remotes/origin/main)
# --oneline shows the commit hash and commit message
# --graph add a * (star symbol) and try to draw a graph, each commit may take more than one line
# oneline graph for blame
git log --graph --abbrev-commit --decorate --format=format:'%C(bold blue)%h%C(reset) - %C(bold green)(%ar)%C(reset) %C(white)%s%C(reset) %C(dim white)- %an%C(reset)%C(bold yellow)%d%C(reset)' --all
# two line graph for blame
git log --graph --abbrev-commit --decorate --format=format:'%C(bold blue)%h%C(reset) - %C(bold cyan)%aD%C(reset) %C(bold green)(%ar)%C(reset)%C(bold yellow)%d%C(reset)%n'' %C(white)%s%C(reset) %C(dim white)- %an%C(reset)'
How view and config git at system/global/local(repo) levels?
# to show config
% git config --list --system
# on mac
fatal: unable to read config file '/etc/gitconfig': No such file or directory
# global config file for unix based OS (linux, macOS) is at ~/.gitconfig, for windows c:\\Users\<username>\.gitconfig
% git config --list --global
user.name=<your_name>
user.email=<your_email>
# local config file location: <repo_path>/.git/config
% git config --list --local
core.repositoryformatversion=0
core.filemode=true
core.bare=false
core.logallrefupdates=true
core.precomposeunicode=true
user.name=<your_name>
user.email=<your_email>
remote.origin.url=git@github.com:<org_or_username>/<repo_name>.git # for ssh connected
# remote.origin.url=https://github.com/<org_or_unsername>/<repo_name>.git # for https connected
remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
branch.main.remote=origin
branch.main.merge=refs/heads/main
- git configuration doc
- where is global config data betterstack
- git config file locations theserverside
I
id
% id # mac
uid=501(<username>) gid=20(staff) groups=20(staff),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),701(com.apple.sharepoint.group.1),33(_appstore),100(_lpoperator),204(_developer),250(_analyticsusers),395(com.apple.access_ftp),398(com.apple.access_screensharing),399(com.apple.access_ssh),400(com.apple.access_remote_ae)
(base) root@43a8fed75479:/# id # linux
uid=0(root) gid=0(root) groups=0(root)
IO redirection
<command> > /dev/null # redirect standard output to be discarded
<command> > /dev/null 2>&1 # reroute stdout and stderr to be drscarded
nohup myscript.sh >myscript.log 2>&1 </dev/null &
#\__/ \___________/ \__/ \________/ ^
# | | | | |
# | | | | run in background
# | | | |
# | | | don't expect input
# | | |
# | | redirect stderr to stdout
# | |
# | redirect stdout to myscript.log
# |
# keep the command running
# no matter whether the connection is lost or you logout
J
jobs
$ jobs # list jobs
[1] + suspended (tty output) vim
S
shell
$ echo $SHELL
/bin/zsh # mac os 15 default
/bin/bash # linux default
U
ulimit
(base) root@43a8fed75479:/# ulimit -a # docker container from image condaforge/miniforge-pypy3
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 31325
max locked memory (kbytes, -l) unlimited
max memory size (kbytes, -m) unlimited
open files (-n) 1048576
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) unlimited
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
(base) root@43a8fed75479:/# cat /proc/sys/fs/file-max
801566
(base) root@43a8fed75479:/# cat /proc/sys/fs/file-nr
352 0 801566
% ulimit -a # mac os single admin user
-t: cpu time (seconds) unlimited
-f: file size (blocks) unlimited
-d: data seg size (kbytes) unlimited
-s: stack size (kbytes) 8176
-c: core file size (blocks) 0
-v: address space (kbytes) unlimited
-l: locked-in-memory size (kbytes) unlimited
-u: processes 4000
-n: file descriptors 256
% ulimit -Hn
unlimited
% ulimit -Sn
256
File Descriptor (wiki) limit references:
- limits on the number of file descriptors unix stack exchange question
- linux kernel file-max and file-nr doc
- limits on the number of linux file descriptors Baeldung
- increase max for file descriptors cyberciti
uname
uname -s # os name,e.g., GNU/Linux, Darwin(mac)
(base) root@43a8fed75479:/# uname -r # linux
6.10.14-linuxkit
% uname -r # mac
24.2.0
(base) root@43a8fed75479:/# uname -v # linux
#1 SMP Thu Oct 24 19:28:55 UTC 2024
% uname -v # mac
Darwin Kernel Version 24.2.0: Fri Dec 6 18:51:28 PST 2024; root:xnu-11215.61.5~2/RELEASE_ARM64_T8112
uname -m # platform x86_64, arm64
MacOS Darwin name references:
- https://apple.stackexchange.com/questions/401832/why-is-macos-often-referred-to-as-darwin
- https://en.wikipedia.org/wiki/Darwin_(operating_system)
- https://www.howtogeek.com/295067/why-is-macos-software-sometimes-labeled-darwin/
W
which
How to find the file location/path of the executable/command?
Sometimes you may have different versions of the executable from different sources installed. Once I encountered a unique bug caused by the jq installed with conda shadowing the other jq installed with homebrew.
$ which whoami
/usr/bin/whoami
X
xclip
# copy current dir to xclip
pwd | xclip
# copy to clipboard, can be pasted in gui, e.g., in firefox
pwd | xclip -sel clip
# paste from xclip
xclip -o
xrdp
sudo yum update
sudo yum install xrdp x11rdp xorgxrdp
sudo /etc/init.d/xrdp status
# result should be
xrdp is stopped
xrdp-sesman is stopped
update cert when cert auto-renew
MY_CERT_MS=com.<domain>.certificates.<username>.aka.corp.<domain>.com-STANDARD_SSL_SERVER_INTERNAL_ENDPOINT-RSA
# retrieve the certificate the private key
<command1> -t Certificate $MY_CERT_MS | openssl x509 -inform DER | sudo tee /etc/xrdp/cert.pem > /dev/null
<command1> -t PrivateKey $MY_CERT_MS | openssl pkcs8 -nocrypt -inform DER -outform PEM | sudo tee /etc/xrdp/key.pem > /dev/null
sudo chmod 400 /etc/xrdp/key.pem /etc/xrdp/cert.pem
sudo /etc/init.d/xrdp restart
sudo /etc/init.d/xrdp status
References
- multi-lingual manpages.org
- Michael Kerrisk man-pages