Posts Tagged ‘e-book’


Following on from a recent post Nmap Cheat Sheet’I have decided to create another cheat sheet but this time for GNU/Linux as I am constantly referring to it for reference. These kind of things are very handy as if you are like myself and don’t use Linux on a daily basis they can play a major part in jogging the little grey cells.

Download:  Cheat Sheet commands for GNU/Linux

CheatSheet commands for GNU / Linux

System Information

1. arch: show the architecture of the machine (1).
2. uname -m: show the architecture of the machine (2)..
3. uname -r: show the kernel version used.
4. dmidecode -q: display the components (hardware) system.
5. hdparm -i /dev/hda: show the characteristics of a hard disk.
6. hdparm -tT /dev/sda: make reading test on a hard disk.
7. cat /proc/cpuinfo: CPU information show.
8. cat /proc/interrupts: show interrupts.
9. cat /proc/meminfo: verify memory usage.
10. cat /proc/swaps: show swap files.
11. cat /proc/version: display the version of the kernel.
12. cat /proc/net/dev: network adapters and display statistics.
13. cat /proc/mounts: display the mounted file system.
14. lspci -tv: show PCI devices.
15. lsusb -tv: show USB devices.
16. date: display the system date.
17. cal 2013: show calendar 2013.
18. cal 07 2013: show the calendar for the month July 2013.
19. date 041217002013.00: place (declare, set) date and time.
20. clock -w: save changes to the BIOS date.

Shutdown (Reset System or Log out)

1. shutdown -h now: Shut down system (1).
2. init 0: Shut down system (2).
3. telinit 0: Shut down system (3).
4. halt: shutdown the system (4).
5. shutdown -h hours:minutes &: planned shutdown of the system.
6. shutdown -c: cancel a planned shutdown of the system.
7. shutdown -r now: Restart (1).
8. reboot: Reboot (2).
9. logout: close session.

Files and Directories

1. cd /home: enter the “home” directory.
2. cd ..: go back one level.
3. cd ../..: back 2 levels.
4. cd: go to the root directory.
5. cd ~user1: go to directory user1.
6. cd -: go (back) to the previous directory.
7. pwd: : show the path of the working directory.
8. ls: see the files in a directory.
9. ls -F: see the files in a directory.
10. ls -l: show details of files and folders in a directory.
11. ls -a: show hidden files.
12. ls *[0-9]*: show the files and folders that contain numbers.
13. tree: display files and folders in a tree starting from the root. (1)
14. lstree: display files and folders in a tree starting from the root. (2)
15. mkdir dir1: create a folder or directory called ‘dir1’.
16. mkdir dir1 dir2: create two folders or directories simultaneously (Create two directories at once)
17. mkdir -p /tmp/dir1/dir2: create a directory tree.
18. rm -f file1: delete the file called file1.
19. rmdir dir1: delete the folder called dir1.
20. rm -rf dir1: delete a folder called dir1 with its contents recursively.
21. rm -rf dir1 dir2: delete two folders (directories) with its contents recursively.
22. mv dir1 new_dir: rename or move a file or folder (directory).
23. cp file1: copy a file.
24. cp file1 file2: copy two files together.
25. cp dir /* . : copy all the files in a directory within the current working directory.
26. cp -a /tmp/dir1 . : copy a directory within the current working directory.
27. cp -a dir1: copy a directory.
28. cp -a dir1 dir2: copy two directories.
29. ln -s file1 lnk1: create a symbolic link to the file or directory.
30. ln file1 lnk1: creating a physical link to the file or directory.
31. touch -t 0712250000 file1: modify the real time (time of creation) of a file or directory.
32. file file1: output (screen dump)
33. iconv -l: lists of known encryption.
34. iconv -f fromEncoding -t toEncoding inputFile > outputFile: creates a new form of the input file is encoded in assuming and making a ToEncoding fromEncoding.
35. find . -maxdepth 1 -name *.jpg -print -exec convert ”{}” -resize 80×60 “thumbs/{}” \;: grouping resized files in the current directory and send them to directories in thumbnail view (requires converting from ImageMagick).

Finding Files

1. find / -name file1: file and directory search from the root of the system.
2. find / -user user1: find files and directories belonging to user user1.
3. find /home/user1 -name \*.bin: search files with extension ‘. bin ‘directory within it’ / home/user1.
4. find /usr/bin -type f -atime +100: look at binary files used in the last 100 days.
5. find /usr/bin -type f -mtime -10: find the changed files created within the last 10 days.
6. find / -name \*.rpm -exec chmod 755 ‘{}’ \;: look for files with extension. ‘rpm’ and change permissions.
7. find / -xdev -name \*.rpm: Find files with extension ‘. rpm’ ignoring them removable devices such as cdrom, pen-drive, etc ….
8. locate \*.ps: find files with extension. ‘ps’ primarily executed with the command ‘updatedb’.
9. whereis halt: show the location of a binary file. In this case you are wondering Where he command ‘halt’
10. which halt: show the full path (full path to it) to a binary / executable.

Mounting a file system

1. mount /dev/hda2 /mnt/hda2: mount a disk called hda2. Check first the existence of the directory ‘/ mnt/hda2?, If not, create it.
2. umount /dev/hda2: removing a disk called hda2. Out first from point ‘/ mnt/hda2.
3. fuser -km /mnt/hda2: force umount when the device is busy.
4. umount -n /mnt/hda2: running disassembly without reading the file / etc / mtab. Useful when the file is read-only or the hard drive is full.
5. mount /dev/fd0 /mnt/floppy: mount a floppy disk (floppy).
6. mount /dev/cdrom /mnt/cdrom: mount a cdrom / dvdrom.
7. mount /dev/hdc /mnt/cdrecorder: mount a rewritable cd or dvdrom.
8. mount /dev/hdb /mnt/cdrecorder: mount a rewritable cd / dvdrom (a dvd).
9. mount -o loop file.iso /mnt/cdrom: mount a file or iso image.
10. mount -t vfat /dev/hda5 /mnt/hda5: mount a FAT32 file system.
11. mount /dev/sda1 /mnt/usbdisk: mount a usb thumb drive or a memory (without specifying the filesystem type).

Hard Disk Space

1. df -h: display a list of mounted partitions.
2. ls -lSr |more: show the size of the files and directories sorted by size.
3. du -sh dir1: Estimate the space used by the directory dir1.
4. du -sk * | sort -rn: show the size of the files and directories sorted by size.
5. rpm -q -a –qf ‘%10{SIZE}t%{NAME}n’ | sort -k1,1n: show space used by the installed rpm packages organized by size (Fedora, Redhat and others).
6. dpkg-query -W -f=’${Installed-Size;10}t${Package}n’ | sort -k1,1n: show space used by the packages installed, organized by size (Ubuntu, Debian and others) .

Users and Groups

1. groupadd name_of_the_group: create a new group.
2. groupdel name_of_the_group: delete a group.
3. groupmod -n new_name_of_the_group old_name_of_the_group: rename a group.
4. useradd -c “Name Surname ” -g admin -d /home/user1 -s /bin/bash user1: Create a new user belonging to the “admin”.
5. useradd user1: create a new user.
6. userdel -r user1: delete a user (‘-r’ eliminates home directory).
7. usermod -c “User FTP” -g system -d /ftp/user1 -s /bin/nologin user1: change user attributes.
8. passwd: Changing password.
9. passwd user1: change the password of a user (only root).
10. chage -E 2013-12-31 user1: place a time limit for the user’s password. In this case says that the key expires on December 31, 2013.
11. pwck: correct syntax check the file format of ‘/ etc / passwd’ and the existence of users.
12. grpck: check correct syntax and format of the file ‘/ etc / group’ and the existence of groups.
13. newgrp group_name: Registers a new group to change the default group of newly created files.

File Permissions (Use “+” to place permissions and “-” to remove)

1. ls -lh: Show permissions.
2. ls /tmp | pr -T5 -W$COLUMNS: Terminal divided into 5 columns.
3. chmod ugo+rwx directory1: : enable read permissions (r) , write (w) and execute (x) to the owner (u) group (g) and others (o) on the directory ‘directory1
4. chmod go-rwx directory1: remove read permission (r), write (w) and (x) running the group (g) and others (o) on the directory ‘directory1
5. chown user1 file1: cchange owner of a file.
6. chown -R user1 directory1: change the owner of a directory and all files and directories contained within.
7. chgrp group1 file1: changing group of files.
8. chown user1:group1 file1: change user and group ownership of a file.
9. find / -perm -u+s: display all system files with SUID configured.
10. chmod u+s /bin/file1: set the SUID bit on a binary file. The user that running that file takes the same privileges as the owner.
11. chmod u-s /bin/file1: disable SUID bit on a binary file.
12. chmod g+s /home/public: place a SGID bit on a directory-similar to SUID but for directory.
13. chmod g-s /home/public: disable SGID bit on a directory.
14. chmod o+t /home/public: place a bit STIKY in a directory. Allows deletion of files only rightful owners.
15. chmod o-t /home/public: STIKY disable bit in a directory.

Special Attributes on files (Use “+” to place permissions and “-” to remove)

1. chattr +a file1: allows to writte by opening a file only append mode.
2. chattr +c file1: allows a file to be compressed / decompressed automatically.
3. chattr +d file1: ensures that the program ignore delete files during backup.
4. chattr +i file1: convert the file unchanged, so it can not be removed, altered, renamed, or bound.
5. chattr +s file1: allows a file to be deleted safely.
6. chattr +S file1: ensures that a file is modified, the changes are written in synchronous mode as with sync.
7. chattr +u file1: allows you to restore the contents of a file even if it is canceled.
8. lsattr: show special attributes.

Compressed files

1. bunzip2 file1.bz2: decompress in file called ‘file1.bz2.
2. bzip2 file1: compress a file called file1.
3. gunzip file1.gz: decompress a file called ‘file1.gz.
4. gzip file1: compress a file called ‘file1.
5. gzip -9 file1: compress with maximum compression.
6. rar a file1.rar test_file: create a zip file called ‘file1.rar’.
7. rar a file1.rar file1 file2 dir1: compress ‘file1,’ file2 and ‘dir1Simultaneously.
8. rar x file1.rar: decompress rar file.
9. unrar x file1.rar: decompress rar file.
10. tar -cvf archive.tar file1: create an uncompressed tarball.
11. tar -cvf archive.tar file1 file2 dir1: create an archive containing ‘file1,file2 and dir1.
12. tar -tf archive.tar: show contents a file.
13. tar -xvf archive.tar: extract a tarball.
14. tar -xvf archive.tar -C /tmp: extract a tarball in / tmp.
15. tar -cvfj archive.tar.bz2 dir1: create a tarball compressed into bzip2.
16. tar -xvfj archive.tar.bz2: decompress a bzip2 compressed tar file.
17. tar -cvfz archive.tar.gz dir1: create a gzip tarball.
18. tar -xvfz archive.tar.gz: decompress a gzip compressed tar archive.
19. zip file1: create a zip file.
20. zip -r file1 file2 dir1: compress in zip several files and directories simultaneously.
21. unzip decompress a zip file.

RPM Packages (Red Hat, Fedora…etc)

1. rpm -ivh package.rpm: install an rpm package.
2. rpm -ivh –nodeeps package.rpm: installing an rpm package ignoring dependencies requests.
3. rpm -U package.rpm: upgrade a rpm package without changing configuration files.
4. rpm -F package.rpm: upgrade a rpm package only if it is installed.
5. rpm -e package_name.rpm: remove a rpm package.
6. rpm -qa: show all rpm packages installed on the system.
7. rpm -qa | grep httpd: show all rpm packages with the name “httpd”.
8. rpm -qi package_name: get information on a specific package installed.
9. rpm -qg “System Environment/Daemons”: show rpm packages of a software group.
10. rpm -ql package_name: show list of files given by a rpm package installed.
11. rpm -qc package_name: show configuration files list given by a rpm package installed.
12. rpm -q package_name –whatrequires: show list of dependencies required for a rpm package.
13. rpm -q package_name –whatprovides: show the capacity provided by a rpm package.
14. rpm -q package_name –scripts: scripts show started during installation / removal.
15. rpm -q package_name –changelog: display the history of revisions of a rpm package.
16. rpm -qf /etc/httpd/conf/httpd.conf: check which rpm package belongs to a given file.
17. rpm -qp package.rpm -l: show list of files given by a rpm package not yet been installed.
18. rpm –import /media/cdrom/RPM-GPG-KEY: Import digital signature public key.
19. rpm –checksig package.rpm: verify the integrity of a package rpm.
20. rpm -qa gpg-pubkey: verify the integrity of all rpm packages installed.
21. rpm -V package_name: check the file size, licenses, rates, owner, group, check MD5 digest and last modified.
22. rpm -Va: check all rpm packages installed on the system. Use with caution.
23. rpm -Vp package.rpm: verify a rpm package not yet installed.
24. rpm2cpio package.rpm | cpio –extract –make-directories *bin*: extracting executable file from a rpm package.
25. rpm -ivh /usr/src/redhat/RPMS/`arch`/package.rpm: install a package built from a source rpm.
26. rpmbuild –rebuild package_name.src.rpm: build a rpm package from a source rpm.

YUM packages updater (Red Hat, Fedora…etc)

1. yum install package_name: download and install a rpm package..
2. yum localinstall package_name.rpm: This will install an RPM and attempt to resolve all dependencies for you, using your repositories.
3. yum update package_name.rpm: update all rpm packages installed on the system.
4. yum update package_name: upgrade a rpm package.
5. yum remove package_name: remove a rpm package.
6. yum list: list all packages installed on the system.
7. yum search package_name: Find a package repository rpm.
8. yum clean packages: clean a cache erasing downloaded packages.
9. yum clean headers: remove all header files that the system uses to resolve the dependency.
10. yum clean all: delete from the cache packages and header files.

Deb packages (Debian, Ubuntu…etc)

1. dpkg -i package.deb: upgrade a deb package.
2. dpkg -r package_name: remove a deb package.
3. dpkg -l: show all deb packages installed on the system.
4. dpkg -l | grep httpd: show all deb packages with the name “httpd”
5. dpkg -s package_name: to obtain information on a specific package installed on the system.
6. dpkg -L package_name: show list of files given by a package installed on the system.
7. dpkg –contents package.deb: show list of files given by a package not yet installed.
8. dpkg -S /bin/ping: check which package owns a given file.

APT packages updater (Debian, Ubuntu …etc)

1. apt-get install package_name: install / upgrade a deb package.
2. apt-cdrom install package_name: install / upgrade a deb package from cdrom.
3. apt-get update: update the package list.
4. apt-get upgrade: update all installed packages
5. apt-get remove package_name: remove a deb package.
6. apt-get check: check the correct resolution of dependencies.
7. apt-get clean: clean up cache from packages downloaded.
8. apt-cache search searched-package: returns list of packages that corresponds to the series’ wanted packages. ”

View the contents of a file

1. cat file1: view the contents of a file starting from the first row.
2. tac file1: view the contents of a file starting from the last line.
3. more file1: view content along a file.
4. less file1: command like ‘more’ but can save the file movement and backward movement.
5. head -2 file1: see the first two lines of a file.
6. tail -2 file1: see the last two lines of a file.
7. tail -f /var/log/messages: see in real time what has been added to the file.

Text Manipulation

1. cat file1 file2 .. | command <> file1_in.txt_or_file1_out.txt: general syntax for text manipulation using PIPE, STDIN and STDOUT.
2. cat file1 | command( sed, grep, awk, grep, etc…) > result.txt: general syntax to manipulate a text from a file and write the output to a new file.
3. cat file1 | command( sed, grep, awk, grep, etc…) » result.txt: general syntax to manipulate a text from a file and add result in an existing file.
4. grep Aug /var/log/messages: search words “Aug” on file ‘/ var / log / messages’.
5. grep ^Aug /var/log/messages: look for words that begin with “Aug” on file ‘/ var / log / messages’
6. grep [0-9] /var/log/messages: select all lines in the file ‘/ var / log / messages’ that contain numbers.
7. grep Aug -R /var/log/*: search for the string “Aug” in directory ‘/ var / log’ and below.
8. sed ‘s/stringa1/stringa2/g’ example.txt: relocate “string1” with “string2” in example.txt
9. sed ‘/^$/d’ example.txt: delete all blank lines from the example.txt
10. sed ‘/ *#/d; /^$/d’ example.txt: Remove comments and blank lines example.txt
11. echo ‘esempio’ | tr ‘[:lower:]‘ ‘[:upper:]‘: convert lowercase to uppercase
12. sed -e ’1d’ result.txt: deletes the first line of the file sample.txt
13. sed -n ‘/stringa1/p’: display only lines that contain the word “string1”.

Character set and file conversion

1. dos2unix filedos.txt fileunix.txt: convert a text file format from MSDOS to UNIX.
2. unix2dos fileunix.txt filedos.txt: convert a text file format from UNIX to MSDOS.
3. recode ..HTML < page.txt > page.html: convert a text file to html.
4. recode -l | more: show all available format conversions.

Analysis of the file systems

1. badblocks -v /dev/hda1: Check for bad blocks on disk hda1.
2. fsck /dev/hda1: repair / check integrity Linux system file on disk hda1.
3. fsck.ext2 /dev/hda1: repair / check integrity ext 2 file system on disk hda1.
4. e2fsck /dev/hda1: repair / check integrity ext 2 file system on disk hda1.
5. fsck.ext3 /dev/hda1: repair / check integrity ext 3 file system on disk hda1.
6. fsck.vfat /dev/hda1: repair / check integrity ext 3 file system on disk hda1.
7. fsck.msdos /dev/hda1: repair / check integrity of a file from MSDOS system on disk hda1.
8. dosfsck /dev/hda1: repair / check integrity of a file from a DOS system on disk hda1.

Formatting a filesystem

1. mkfs /dev/hda1: create a Linux file system on the partition hda1.
2. mke2fs /dev/hda1: create a system file type on the partition hda1
3. mke2fs -j /dev/hda1: create a Linux file system type ext3 (journal) on hda1 partition.
4. mkfs -t vfat 32 -F /dev/hda1: ccreate a FAT32 file system on hda1.
5. fdformat -n /dev/fd0: flooply format a disk.
6. mkswap /dev/hda3: create a swap file system.

Working with SWAP

1. mkswap /dev/hda3: create a swap file system.
2. swapon /dev/hda3: activate a new swap partition.
3. swapon /dev/hda2 /dev/hdb3: activate two swap partitions.


1. dump -0aj -f /tmp/home0.bak /home: make a complete backup directory ‘/ home’.
2. dump -1aj -f /tmp/home0.bak /home: make incremental backup directory ‘/ home’.
3. restore -if /tmp/home0.bak: restoring a backup interactively.
4. rsync -rogpav –delete /home /tmp: synchronization between directories.
5. rsync -rogpav -e ssh –delete /home ip_address:/tmp: rsync through SSH tunnel.
6. rsync -az -e ssh –delete ip_addr:/home/public /home/local: synchronize a local directory with a remote directory via ssh and compression.
7. rsync -az -e ssh –delete /home/local ip_addr:/home/public: Synchronize a remote directory with a local directory via ssh and compression.
8. dd bs=1M if=/dev/hda | gzip | ssh user@ip_addr ‘dd of=hda.gz’: make a backup on a hard disk on a remote host via ssh.
9. dd if=/dev/sda of=/tmp/file1: save the contents of a hard drive to a file. (In this case the hard drive is “sda” and the file “file1”).
10. tar -Puf backup.tar /home/user: make incremental backup directory ‘/ home / user’.
11. ( cd /tmp/local/ && tar c . ) | ssh -C user@ip_addr ‘cd /home/share/ && tar x -p’: copy the contents of a directory on a remote directory via ssh.
12. ( tar c /home ) | ssh -C user@ip_addr ‘cd /home/backup-home && tar x -p’: copy a local directory on a remote directory via ssh.
13. tar cf – . | (cd /tmp/backup ; tar xf – ): local copy preserving permits and links from one directory to another.
14. find /home/user1 -name ‘*.txt’ | xargs cp -av –target-directory=/home/backup/ –parents: finding and copying all files with ‘. txt’ from one directory to another.
15. find /var/log -name ‘*.log’ | tar cv –files-from=- | bzip2 > log.tar.bz2: find all files with ‘. log’ and make a bzip file.
16. dd if=/dev/hda of=/dev/fd0 bs=512 count=1: make a copy of MRB (Master Boot Record) to floppy.
17. dd if=/dev/fd0 of=/dev/hda bs=512 count=1: restore the backup of the MBR (Master Boot Record) saved on a floppy.


1. cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force: clean or erase a rewritable cd.
2. mkisofs /dev/cdrom > cd.iso: create an iso image of cdrom on disk.
3. mkisofs /dev/cdrom | gzip > cd_iso.gz: create a compressed iso image of cdrom on disk.
4. mkisofs -J -allow-leading-dots -R -V “Label CD” -iso-level 4 -o ./cd.iso data_cd: create an iso image from a directory.
5. cdrecord -v dev=/dev/cdrom cd.iso: burn an iso image.
6. gzip -dc cd_iso.gz | cdrecord dev=/dev/cdrom -: burn an iso image compression.
7. mount -o loop cd.iso /mnt/iso: mount an iso image.
8. cd-paranoia -B: take songs from a cd to wav files.
9. cd-paranoia – ”-3”: take the first 3 songs from a CD to wav files.
10. cdrecord –scanbus: scan bus to identify the channel scsi.
11. dd if=/dev/hdc | md5sum: to run an md5sum in a device such as a cd.

LAN and Wi-Fi

1. ifconfig eth0: show the configuration of an Ethernet network card.
2. ifup eth0: activate an interface ‘eth0’
3. ifdown eth0: disable an interface ‘eth0’
4. ifconfig eth0 netmask set an IP address.
5. ifconfig eth0 promisc: configure ‘eth0’ common mode for packets (sniffing).
6. dhclient eth0: active interface ‘eth0’ dhcp mode.
7. route -n: show route table
8. route add -net 0/0 gw IP_Gateway: default input configuration.
9. route add -net netmask gw Configure static route for network search ‘192 .168.0.0/16’
10. route del 0/0 gw IP_gateway: remove the static route.
11. echo “1” > /proc/sys/net/ipv4/ip_forward: enable ip route.
12. hostname: display the system hostname.
13. host hostname search to resolve the name to an IP address (1).
14. nslookup find the host name to resolve the name to an IP address and vice versa (2)
15. ip link show: show the link status of all interfaces.
16. mii-tool eth0: show the link status of ‘eth0’
17. ethtool eth0: display statistics for ‘eth0’.
18. netstat -tup: show all active network connections and their PID.
19. netstat -tupl: show all network services listening on the system and its PID.
20. tcpdump tcp port 80: show all HTTP traffic.
21. iwlist scan: show wireless networks.
22. iwconfig eth1: show the configuration of a wireless network card.
23. whois search Whois database.

Microsoft Windows Networks (SAMBA)

1. nbtscan ip_addr: net bios name resolution.
2. nmblookup -A ip_addr: net bios name resolution.
3. smbclient -L ip_addr/hostname: show remote actions of a windows host.


1. iptables -t filter -L: show all chains of the filter table.
2. iptables -t nat -L: show all chains of the nat table.
3. iptables -t filter -F: clear all rules from the filter table.
4. iptables -t nat -F: clean all nat table rules.
5. iptables -t filter -X: delete any user-created chain.
6. iptables -t filter -A INPUT -p tcp –dport telnet -j ACCEPT: allow input telnet connections.
7. iptables -t filter -A OUTPUT -p tcp –dport http -j DROP: block output HTTP connections.
8. iptables -t filter -A FORWARD -p tcp –dport pop3 -j ACCEPT: allow POP connections to a front chain.
9. iptables -t filter -A INPUT -j LOG –log-prefix “DROP INPUT”: registering an input string.
10. iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE: configure a PAT (Port Address Translation) on eth0, hiding the forced departure packages.
11. iptables -t nat -A PREROUTING -d -p tcp -m tcp –dport 22 -j DNAT –to-destination redirect packets directed from one host to another.

Monitoring and debugging

1. top: show cpu processes.
2. ps -eafw: show cpu processes.
3. ps -e -o pid,args –forest: shows Linux processes in a hierarchal manner.
4. pstree: show system processes tree.
5. kill -9 ID_Process: force close and finish process..
6. kill -1 ID_Process: force a process to reload the configuration.
7. lsof -p $$: display a list of files opened by processes.
8. lsof /home/user1: lists open files on a given path by the system.
9. strace -c ls >/dev/null: show system calls made ​​and received by a process.
10. strace -f -e open ls >/dev/null: display library calls.
11. watch -n1 ‘cat /proc/interrupts’: show interruptions in real time.
12. last reboot: show reboot history.
13. lsmod: display the loaded kernel.
14. free -m: Displays the status of RAM in megabytes.
15. smartctl -A /dev/hda: monitor the reliability of a hard drive via SMART.
16. smartctl -i /dev/hda: check if SMART is enabled on a hard disk.
17. tail /var/log/dmesg: show events inherent in the charging process of the kernel.
18. tail /var/log/messages: show system events.

Other useful commands

1. apropos …keyword: display a list of commands that belong to the keywords of a program, are useful when you know what makes your program, but not know the command name.
2. man ping: display manual pages on-line, for example, in a ping command, use the ‘-k’ to find any related command.
3. whatis …keyword: Displays the description of what the program does.
4. mkbootdisk –device /dev/fd0 `uname -r`: create a floppy boteable.
5. gpg -c file1: encrypt a file with GNU security guard.
6. gpg file1.gpg: decode a file with GNU Security Guard.
7. wget -r download an entire website.
8. wget -c download a file with the possibility to stop the download and resume later.
9. echo ‘wget -c‘ | at 09:00: Start a download at any time. In this case begin at 9 am.
10. ldd /usr/bin/ssh: display the shared libraries required by ssh.
11. alias hh=’history’: place an alias for a command-hh = history.
12. chsh: change the command Shell.
13. chsh –list-shells: is an appropriate command to find out if you have to remote into another terminal.
14. who -a: show who is registered, and print time of last import system, dead processes, system logging processes, active processes produced by init, current and past performance of the system clock changes.

If you don’t own one of the popular e-book readers like the Kindle or the Sony Reader, you may not realize all the benefits that are built into these devices. Even if you do own one, you may not have discovered all the features available to you. Here are some of the lesser known advantages included with the most popular e-book readers.


  1. Easy on the eyes. The low glare screen is much easier on your eyes than a computer screen. In addition, the font size can be adjusted. No more need for buying large print books.
  2. Highlighting. Many readers of non-fiction books like to be able to underline or highlight key statements in their books. The creators of the e-book readers took this into account and built in that capability as well. Besides allowing you to mark these statements (or even full paragraphs) the e-book reader will collect all your highlights in one area attached to the book. Scroll through all your highlights at once and with one click you can read it in full context as well.
  3. Notes. Some people prefer to go beyond highlighting to actually writing notes in the margins of their books. The e-book reader improves this reader preference as well. You can add a note anywhere in your book. No need to fit it in a margin. The notes are saved together with your book, just like your highlights. In addition, they are typed, which should provide better legibility than small handwritten notations.
  4. Built-in dictionary. This is a really great feature. You can access the dictionary with a single click from any book or magazine you are reading. Click on the word that you are unsure of and the definition pops up for you.
  5. Saves your page. You will never lose your page or forget where you left off in a book when you use an e-book reader. You can come back to a book weeks or months later and it will automatically take you to the page you were reading the last time you had that book open.
  6. Online backup. You will never lose an e-book that you have purchased through Amazon or Barnes and Noble. Even if you should lose or change e-readers, every e-book you purchase remains backed up and available for you to access at no additional charge.
  7. Magazines. In addition to downloading books, you can also have most magazine subscriptions sent to your e-reader as well. This has many benefits. No magazines stacking up in your house. No concerns about magazines being forwarded if you have more than one residence, travel or are moving.
  8. Read it anywhere. If you’ve ever tried to use a laptop computer in bright sunlight, you know that it is almost impossible to see the screen. Since e-readers don’t have backlit screens, they are as easy to read in bright sunlight as a book. In the dark you do need a book light to read these types of screens, but they are inexpensive and available as accessories. E-book applications are also available for iphones, ipads and computers. As stated before, you have access to your library online and this is true no matter which device you use. You also can also read your books with ‘no hands’. Set it down and read while your hands are busy crocheting or knitting. It just takes a quick finger click to turn the page.
  9. Book sharing. This option was not always available but both the Nook and the Kindle now have book loaning options. You can now borrow e-books to or from your friends with similar e-book readers for a limited amount of time.
  10. Audio. Some of the e-book readers have a variety of audio options included as well. You can have the device read to you in the car. You can add music files to your device and play background music while you read. These are options you just can’t get with a paper book.

There are other features as well like web browsing, car chargers, instant downloads, free previews of books and hundreds of free books available for download. Many skeptics have been quickly converted to e-book fans once they discover the benefits of this new technology