Short, sharp and shiny reference to commands that I constantly have to look up while developing and administering Ubuntu systems.
New System
A few steps I tend to perform on a new system.
# Allow sudoers to elevate without typing in their password every time. # Careful! This may be considered a security risk. echo "%sudo ALL=NOPASSWD: ALL" | sudo tee -a /etc/sudoers > /dev/null
Users and Permissions
Users and Groups
Add a user: adduser username
List a user’s groups: groups username
Assume a user’s identity: sudo su - -s /bin/bash username
Set a user’s home directory: sudo usermod --home /dir/dir username
Setting up a new user as an Administrator:
sudo adduser <username>
sudo adduser <username> sudo
sudo adduser <username> adm
sudo adduser <username> lpadmin
File/Directory Ownership
Set owner user/group: chown -R username:groupname directoryname/
Working with Files
Copy from one computer to another: scp [user@]host1:]file1 [user@]host2:]file2
Apt (install software)
Update Lists: sudo apt-get update
Search packages: apt-cache search [search string]
Install Software: sudo apt-get install packagename
Services/Daemons
The following commands vary between daemons, but many actively maintained products are configured to work this way.
Start a daemon: /etc/init.d/servicename start
Stop a daemon: /etc/init.d/servicename stop
Query status of running services: service --status-all
Start a daemon (shorthand): service servicename start
Stop a daemon (shorthand): service servicename stop
Disk Drives and Storage
Get a summary of disk usage in the current folder:
du -s -m *
Find those files taking up all your valuable disk space! (my source: ref).
sudo find . -maxdepth 1 -type d ! -name . -exec du -sh '{}' \; | sort -h
List attached drives (my source: reference). I found this particularly useful when working with AWS.
sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL
NAME FSTYPE SIZE MOUNTPOINT LABEL
xvda 8G
└─xvda1 ext4 8G / cloudimg-rootfs
xvdb ext3 15.3G /mnt
xvdc ext3 15.3G
You can also try sudo fdisk -l for a similar result.
Another useful command is df -h.
GCC
Compile a single file of C++ code to an executable. This command compiles main.cpp to main.exe.
gcc -g -Wall -std=c++0x main.cpp
Append to a File with elevated permissions
echo “append this line of text” | sudo tee -a myfile.txt > /dev/null
Subversion
Delete unversioned files
You can clean up any versioned files with svn revert, but how do you get rid of any files that are not under version control? Here’s how (my source: Guy Rutenburg).
The first command performs a dry run, simply listing the unversioned files. The second command pipes the result of the first to xargs to delete the file.
svn status --no-ignore | grep '^\?' | sed 's/^\? //' svn status --no-ignore | grep '^\?' | sed 's/^\? //' | xargs -Ixx rm -rf xx
Boinst 