Set time and restrict automatic update it with host machine at virtual box :
sudo service vboxadd-service stop
Set custom Date at ubuntu machine :
sudo date -s "3 SEPT 2014 09:18:00"
Copy directory to remote server from remote server
scp -P 22 -r sourcedir/ user@dest.com:/dest/dir/
Run a scheduled rake task(lets say update sphinx indexing on every 30 min periodically) on Lunux crontab:
# find where is your rake(which rake)
#m h dom mon dow user command
*/30 * * * * root /bin/bash -l -c 'searchd --stop -c /var/rails/project/current/config sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k/production.sphinx.conf && cd /var/rails/project/current && RAILS_ENV=production /usr/local/bin/rake ts:rebuild && chmod -R 777 tmp/'
Create Symbolic link(Short cut)
ln -s /source/dir destination/dire/short_cut_name
ln -s -f /source/dir destination/dire/short_cut_name
truncate a file(0 means how many character you wanna keep)
truncate -s0 /path/to/file
see a file's last portion on real time
tail -f path/to/file
See a folder's size
du -hs /path/to/folder
See a file size
du /path/to/file -h
See full disc size
df -h
Search file with pattern and delete them (from a specific directory)
find . -name 'file_name_pattern*' -delete
find . -name '*file_name_pattern' -delete
find running process and kill them by process id forcefully
ps aux | grep rails
kill -9 RAILS_PROCESS_ID
Kill all processes named for example "firefox"
killall firefox
Request to specific port on a server:
telnet SERVER_IP PORT
Zip a folder
zip -r new_zep.zip /folder/path
tar a folder
tar -zcvf compressFileName folderToCompress
tar -xvzf file.tar.gz
Remove recursively a folder's content(keeping the folder itself)
rm -rf /path/to/folder/*
Download
wget download_url -O new_downloaded_file_name
Copy a folder
cp -r source/dir destination/dir
Make folder recursively
mkdir -p /source/f1/f2/...../fn
To know 32 or 64 bit Linux machine
uname -a
To know Ubuntu version
lsb_release -a
How to change timezone on ubuntu:
ln -sf /usr/share/zoneinfo/Asia/Bangkok /etc/localtime
ntpdate th.pool.ntp.org
sudo dpkg-reconfigure tzdata
Better way to run long running Rails Rake Task:
nohup bundle exec rake extract:infogenesis RAILS_ENV=production > rake.out 2&>&1 &
#How to login and then download a file using CURL preserving user loggedin cookie
curl -c cookie.txt -d "username=USERNAME&password=PASSWORD" LOGIN_URL
curl -X POST -b cookie.txt -d 'p1=d1&p2=d2' CSV_EXPORT_URL
# See all running cron tasks(be sure you switch to right user like root) inside ubuntu Machine
crontab -l
# Activating swap memory on ubuntu server
sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k # where swap memory will be double of count
sudo mkswap /swapfile
sudo swapon /swapfile
#Shutdown ubuntu machine automatically after 2 hours
sudo shutdown -h 120
#Linux search a content from a folders containing files
grep -R -i -n 'the-text-you-are-searching-for' *
#For Large Sql Import
SET autocommit=0 ; source the_sql_file.sql ; COMMIT ;
