Skip to content

quick-notes.md

Latest commit

 

History

History
155 lines (110 loc) · 2.65 KB

quick-notes.md

File metadata and controls

155 lines (110 loc) · 2.65 KB

Shell

diff

diff -bu

-b: ignore space change
-u: output NUM (default 3) lines of unified context

redirect

Interpretation from left to right. Pipe read from file descirptor 1.

command 2>&1 >/dev/null | wc -l

This will redirect stderr to stdout, but stderr will not redirect to /dev/null.

command >/dev/null 2>&1 | wc -l

This will redirect stderr to stdout, and stderr will also redirect to /dev/null. But pipe will still get the stderr. > /dev/null will not change the fact that stderr is redirected to pipe.

Resource

Add man pages

export MANPATH="/Applications/X/C/D/P/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/share/man:$MANPATH"

Git

How to rebase your branch

git checkout branchname
git rebase -i master

Change local user name

git config user.name "Your name"
git config user.email "Your email"

Synchronize git branch with master

Git Forks And Upstreams

git checkout branchname
# some work and some commits
# some time passes
git fetch upstream
git rebase upstream/master

Synchronize git master

git checkout master
git fetch upstream
git merge upstream/master (or git rebase upstream/master)

Delete the commit on remote github

See here

First remove the last commit

git rebase -i HEAD~2 ( Or use the option in IDE )

Force push

git push origin +branchname --force

Worktree

It is useful when you want to push a folder to a different branch. For example, push public/ to gh-pages

git worktree add -B gh-pages public upstream/gh-pages

Network

check port being forwarded

netstat -tpln

ssh without password

ssh-keygen -t rsa(with default config)
ssh-copy-id root@172.100.51.192
ssh root@ip.address

overwatch tcp call

Tool: tcpdump

tcpdump -i vmgmt port http and dst www.heise.de

download from remote host

scp your_username@remotehost.edu:foobar.txt /local/dir

System

unmount busy device

umount -l /path/to/busy-device

unmount busy nfs

umount -f /path/to/busy-network-file-system

write random data to file

dd if=/dev/urandom of=sample.txt bs=1G count=1
dd if=/dev/urandom of=sample.txt bs=64M count=16

firewall

/etc/init.d/firewall start
/etc/init.d/firewall stop

Database

show databases;
GRANT ALL ON `DATABASE`.* TO 'user'@'localhost' IDENTIFIED BY 'password';