chmod: 1=x, 2=w, 4=r
chmod (user)(group)(other) chmod 730 # only the user can rwx, read permission to the group or other
chown owner:group file
chmod u=rx file (Give the owner rx permissions, not w)
chmod go-rwx file (Deny rwx permission for group, others)
chmod g+w file (Give write permission to the group)
chmod a+x file1 file2 (Give execute permission to everybody)
chmod g+rx,o+x file (OK to combine like this with a comma)
delta-ironhammer-rails (develop)$ echo 2.4.1 | cat > .ruby-version
delta-ironhammer-rails (develop)$ cat .ruby-version
2.4.1
truncate -s 0 myfile.txt
How to search text files for specific text
grep -rnw '/path/to/somewhere/' -e "pattern"
Find the size of a given subdirectory. [Using du to find troublesome directories](http://unix.stackexchange.com/questions/125429/tracking-down-where-disk-space-has-gone-on-linux
$ du -sh app
120K app
$ du -sh log
82M log
$ ncdu
Development$ du -mh ./ | sort -nr | head -n 20
1004K .//telnyx_omega_pricing/deps/idna/src
968K .//telnyx_omega_pricing/node_modules/babel-runtime
920K .//telnyx_omega_pricing/deps/cowboy
916K .//telnyx_omega_pricing/deps/ecto/lib
916K .//ksm_consulting_sql/deps/ecto
880K .//telnyx_omega_pricing/_build/test/lib/postgrex
880K .//telnyx_omega_pricing/_build/dev/lib/postgrex
879M .//regdata/log
856K .//telnyx_omega_pricing/_build/test/lib/postgrex/ebin
856K .//telnyx_omega_pricing/_build/dev/lib/postgrex/ebin
848K .//telnyx_omega_pricing/deps/ecto/lib/ecto
844K .//telnyx_omega_pricing/_build/test/lib/phoenix
844K .//telnyx_omega_pricing/_build/dev/lib/phoenix
844K .//stock_trend_finder/tmp/cache/assets/development/sass/9bbc4a709c49c4730b532bd57984d33d03c90ee4
844K .//stock_trend_finder/tmp/cache/assets/development/sass/50b9864b5cefbea17955e7430fab95f1f478681a
844K .//stock_trend_finder/tmp/cache/assets/development/sass/0db7b347458fb0c41e1987d6ef712ea64ddeb0de
844K .//regdata/.git/objects/0a
836K .//stock_trend_finder/tmp/cache/assets/development/sass/d95b5980363d60d8ce51dfb4512674db9ea2beb4
836K .//stock_trend_finder/.git/objects/ae
Development$ du -sh ./* | sort -nr
340K ./ystock
280K ./telnyx_omega_pricing_rails
120K ./stocktwits-api-ruby
71M ./telnyx_omega_pricing
37M ./tdameritrade_api
34M ./pricemap
6.5M ./ksm_consulting_sql
2.1G ./stock_trend_finder
Alternative method:
$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 32G 8.0K 32G 1% /dev
tmpfs 6.3G 416K 6.3G 1% /run
/dev/xvda1 7.8G 6.5G 909M 88% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 5.0M 0 5.0M 0% /run/lock
none 32G 0 32G 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/xvdf 3.9T 2.4T 1.4T 64% /mnt/new
/etc/fstab - file with the drive mounts
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 10G 0 disk
└─xvda1 202:1 0 10G 0 part /
xvdb 202:16 0 3G 0 disk
$ sudo file -s /dev/xvdb
/dev/xvdb: data
$ sudo mkfs -t ext4 /dev/xvdb
$ sudo mount /dev/xvdb /pgdata
Create symbolic link:
ln -s [TARGET DIRECTORY OR FILE] ./[SHORTCUT]
-sfv switch commonly used:
-b, --backup[=Control]: Backup each existing destination file
-d, -F, --directory: Hard link directories (super-user only)
-f, --Force: Remove existing destination file(s)
-n, --no-dereference: Treat destination that is a symlink to a directory as if it were a normal file.
-i, --interactive: Prompt whether to remove destinations
-s, --symbolic: Make symbolic links instead of hard links -S [suffix], --suffix=[Suffix]: Override the usual backup suffix. See below
-target-directory=[directory]: Specify the directory in which to create the links.
-v, --verbose: Print name of each file before linking.
View all background tasks:
ps -ef
ps -ax | grep <application name>
pkill kills processes by name
pkill -f processname
kill -9 <pid>
Echo curl request header & body without sending it?
nc -l localhost 8000
PRODUCTION ubuntu@ip-172-30-0-78:~$ netstat -nlt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:5432 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp6 0 0 :::3030 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN
Add existing user tony to ftp supplementary/secondary group with the usermod command using the -a option ~ i.e. add the user to the supplemental group(s). Use only with -G option:
usermod -a -G ftp tony
In this example, change tony user’s primary group to www, enter:
usermod -g www tony
scp <file_source> <file_dest>
scp /mnt/mysql/dump/fi_app_metadata.sql ~/Development/fi_app_metadata.sql
To get a file from remote to local (from local terminal):
$ scp ubuntu@fidb-staging:/mnt/mysql/dump/*_20170320.sql /Users/wkotzan/Development/
banks_20170320.sql 100% 2035KB 2.0MB/s 00:01
sites_20170320.sql 100% 4458KB 2.2MB/s 00:02
ssh -L local_port:remote_address:remote_port [email protected]
set -x - sets up a mode to display all commands in the script to terminal