Useful Linux Commands

Another post in English, just like the Nintendo DS How-To. I think the following commands will be a usefull reference for future use and maybe a «cheat-sheet». I list them in categories for easier access. If you have any suggestions, questions, want to correct something or want to add a command, feel free to comment below.

Networking Commands:

• ethtool eth0 Shows status of ethernet interface eth0.
• iwconfig eth1 Shows status of the wireless interface eth1.
• iwlist scan Lists all wireless networks in range.
• ip route show Lists routing table.
• netstat -tupl Lists internet services on a system.
• netstat -tup Lists active connections to/from a system.
• hostname -i Shows localhost IP.

Windows Networking Commands (Samba):

• smbtree Lists all Windows machines in a network. (See also findsmb)
• smbclient -L windows_box Lists shares on windows machine or samba server.
• mount -t smbfs -o fmask=666,guest //windows_box/share /mnt/share Mount a windows share.
• nmblookup -A 1.2.3.4 Finds the Windows (netbios) name associated with IP address.

Secure Shell (SSH):

• ssh $USER@$HOST command Runs command on $HOST as $USER.
• ssh -g -L 8080:localhost:80 root@$HOST Forwards connections to $HOSTNAME:8080 out to $HOST:80.
• ssh -R 1434:imap:143 root@$HOST Forwards connections from $HOST:1434 in to imap:143.

Archives and Compression:

• gpg -c file Encrypts a file.
• gpg file.gpg Decrypts a file.

CDs:

• gzip < /dev/cdrom > cdrom.iso.gz Saves a copy of a data cd-rom.
• mkisofs -V LABEL -r dir | gzip > cdrom.iso.gz Creates cd-rom image from contents of a dir.
• mount -o loop cdrom.iso /mnt/dir Mounts the cdrom image at /mnt/dir (read only).
• cdparanoia -B Rips audio tracks from CD to wav files in current dir.
• oggenc --tracknum='track' track.cdda.wav -o 'track.ogg' Makes ogg file from wav file.

Disk Usage/Space:

• fdisk -l Shows disks partitions sizes and types (run as root -> sudo fdisk -l).
• df -h Shows free space on mounted filesystems.

Monitoring/Logging:

• tcpdump not port 22 Shows network traffic except SSH.
• last reboot Shows system reboot history.
• free -m Shows amount of (remaining) RAM (-m displays in MB).

System Information:

• uname -a Shows kernel version and system architecture.
• head -n1 /etc/issue Shows name and version of distribution.
• cat /proc/partitions Shows all partitions registered on the system.
• grep MemTotal /proc/meminfo Shows RAM total seen by the system.
• grep "model name" /proc/cpuinfo Shows CPU(s) info.
• mount | column -t Lists mounted filesystems on the system (and align output).
• hdparm -i /dev/sda Shows info about disk sda.