Liste de commandes à connaitre (b)

Text Manipulation
cat file1 file2 ... | command <> file1_in.txt_or_file1_out.txt general syntax for text manipulation using PIPE, STDIN and STDOUT
cat file1 | command( sed, grep, awk, grep, etc...) > result.txt general syntax to manipulate a text of a file, and write result to a new file
cat file1 | command( sed, grep, awk, grep, etc...) >> result.txt general syntax to manipulate a text of a file and append result in existing file
grep Aug /var/log/messages look up words "Aug" on file '/var/log/messages'
grep ^Aug /var/log/messages look up words that begin with "Aug" on file '/var/log/messages'
grep [0-9] /var/log/messages select from file '/var/log/messages' all lines that contain numbers
grep Aug -R /var/log/* search string "Aug" at directory '/var/log' and below
sed 's/stringa1/stringa2/g' example.txt replace "string1" with "string2" in example.txt
sed '/^$/d' example.txt remove all blank lines from example.txt
sed '/ *#/d; /^$/d' example.txt remove comments and blank lines from example.txt
echo 'esempio' | tr '[:lower:]' '[:upper:]' convert from lower case in upper case
sed -e '1d' result.txt eliminates the first line from file example.txt
sed -n '/stringa1/p' view only lines that contain the word "string1"
sed -e 's/ *$//' example.txt remove empty characters at the end of each row
sed -e 's/stringa1//g' example.txt remove only the word "string1" from text and leave intact all
sed -n '1,5p;5q' example.txt view from 1th to 5th row
sed -n '5p;5q' example.txt view row number 5
sed -e 's/00*/0/g' example.txt replace more zeros with a single zero
cat -n file1 number row of a file
cat example.txt | awk 'NR%2==1' remove all even lines from example.txt
echo a b c | awk '{print $1}' view the first column of a line
echo a b c | awk '{print $1,$3}' view the first and third column of a line
paste file1 file2 merging contents of two files for columns
paste -d '+' file1 file2 merging contents of two files for columns with '+' delimiter on the center
sort file1 file2 sort contents of two files
sort file1 file2 | uniq sort contents of two files omitting lines repeated
sort file1 file2 | uniq -u sort contents of two files by viewing only unique line
sort file1 file2 | uniq -d sort contents of two files by viewing only duplicate line
comm -1 file1 file2 compare contents of two files by deleting only unique lines from 'file1'
comm -2 file1 file2 compare contents of two files by deleting only unique lines from 'file2'
comm -3 file1 file2 compare contents of two files by deleting only the lines that appear on both files

Character set and Format file conversion
dos2unix filedos.txt fileunix.txt convert a text file format from MSDOS to UNIX
unix2dos fileunix.txt filedos.txt convert a text file format from UNIX to MSDOS
recode ..HTML < page.txt > page.html convert a text file to html
recode -l | more show all available formats conversion

Filesystem Analysis
badblocks -v /dev/hda1 check bad blocks in disk hda1
fsck /dev/hda1 repair / check integrity of linux filesystem on disk hda1
fsck.ext2 /dev/hda1 repair / check integrity of ext2 filesystem on disk hda1
e2fsck /dev/hda1 repair / check integrity of ext2 filesystem on disk hda1
e2fsck -j /dev/hda1 repair / check integrity of ext3 filesystem on disk hda1
fsck.ext3 /dev/hda1 repair / check integrity of ext3 filesystem on disk hda1
fsck.vfat /dev/hda1 repair / check integrity of fat filesystem on disk hda1
fsck.msdos /dev/hda1 repair / check integrity of dos filesystem on disk hda1
dosfsck /dev/hda1 repair / check integrity of dos filesystems on disk hda1

Format a Filesystem
mkfs /dev/hda1 create a filesystem type linux on hda1 partition
mke2fs /dev/hda1 create a filesystem type linux ext2 on hda1 partition
mke2fs -j /dev/hda1 create a filesystem type linux ext3 (journal) on hda1 partition
mkfs -t vfat 32 -F /dev/hda1 create a FAT32 filesystem
fdformat -n /dev/fd0 format a floppy disk
mkswap /dev/hda3 create a swap filesystem

SWAP filesystem
mkswap /dev/hda3 create a swap filesystem
swapon /dev/hda3 activating a new swap partition
swapon /dev/hda2 /dev/hdb3 activate two swap partitions

Backup
dump -0aj -f /tmp/home0.bak /home make a full backup of directory '/home'
dump -1aj -f /tmp/home0.bak /home make a incremental backup of directory '/home'
restore -if /tmp/home0.bak restoring a backup interactively
rsync -rogpav --delete /home /tmp synchronization between directories
rsync -rogpav -e ssh --delete /home ip_address:/tmp rsync via SSH tunnel
rsync -az -e ssh --delete ip_addr:/home/public /home/local synchronize a local directory with a remote directory via ssh and compression
rsync -az -e ssh --delete /home/local ip_addr:/home/public synchronize a remote directory with a local directory via ssh and compression
dd bs=1M if=/dev/hda | gzip | ssh user@ip_addr 'dd of=hda.gz' make a backup of a local hard disk on remote host via ssh
dd if=/dev/sda of=/tmp/file1 backup content of the harddrive to a file
tar -Puf backup.tar /home/user make a incremental backup of directory '/home/user'
( cd /tmp/local/ && tar c . ) | ssh -C user@ip_addr 'cd /home/share/ && tar x -p' copy content of a directory on remote directory via ssh
( tar c /home ) | ssh -C user@ip_addr 'cd /home/backup-home && tar x -p' copy a local directory on remote directory via ssh
tar cf - . | (cd /tmp/backup ; tar xf - ) local copy preserving permits and links from a directory to another
find /home/user1 -name \*.txt | xargs cp -av --target-directory=/home/backup/ --parents find and copy all files with '.txt' extention from a directory to another
find /var/log -name *.log | tar cv --files-from=- | bzip2 > log.tar.bz2 find all files with '.log' extention and make an bzip archive
dd if=/dev/hda of=/dev/fd0 bs=512 count=1 make a copy of MBR (Master Boot Record) to floppy
dd if=/dev/fd0 of=/dev/hda bs=512 count=1 restore MBR from backup copy saved to floppy

CDROM
cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -force clean a rewritable cdrom
mkisofs /dev/cdrom > cd.iso create an iso image of cdrom on disk
mkisofs /dev/cdrom | gzip > cd_iso.gz create a compressed iso image of cdrom on disk
mkisofs -J -allow-leading-dots -R -V "Label CD" -iso-level 4 -o ./cd.iso data_cd create an iso image of a directory
cdrecord -v dev=/dev/cdrom cd.iso burn an ISO image
gzip -dc cd_iso.gz | cdrecord dev=/dev/cdrom - burn a compressed ISO image
mount -o loop cd.iso /mnt/iso mount an ISO image
cd-paranoia -B rip audio tracks from a CD to wav files
cd-paranoia -- "-3" rip first three audio tracks from a CD to wav files
cdrecord --scanbus scan bus to identify the channel scsi
dd if=/dev/hdc | md5sum perform an md5sum on a device, like a CD

Networking (LAN and WiFi)
ifconfig eth0 show configuration of an ethernet network card
ifup eth0 activate an interface 'eth0'
ifdown eth0 disable an interface 'eth0'
ifconfig eth0 192.168.1.1 netmask 255.255.255.0 configure IP Address
ifconfig eth0 promisc configure 'eth0' in promiscuous mode to gather packets (sniffing)
dhclient eth0 active interface 'eth0' in dhcp mode
route -n show routing table
route add -net 0/0 gw IP_Gateway configura default gateway
route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1 configure static route to reach network '192.168.0.0/16'
route del 0/0 gw IP_gateway remove static route
echo "1" > /proc/sys/net/ipv4/ip_forward activate ip routing
hostname show hostname of system
host www.example.com lookup hostname to resolve name to ip address and viceversa(1)
nslookup www.example.com lookup hostname to resolve name to ip address and viceversa(2)
ip link show show link status of all interfaces
mii-tool eth0 show link status of 'eth0'
ethtool eth0 show statistics of network card 'eth0'
netstat -tup show all active network connections and their PID
netstat -tupl show all network services listening on the system and their PID
tcpdump tcp port 80 show all HTTP traffic
iwlist scan show wireless networks
iwconfig eth1 show configuration of a wireless network card
hostname show hostname
host www.example.com lookup hostname to resolve name to ip address and viceversa
nslookup www.example.com lookup hostname to resolve name to ip address and viceversa
whois www.example.com lookup on Whois database

Microsoft Windows networks (SAMBA)
nbtscan ip_addr netbios name resolution
nmblookup -A ip_addr netbios name resolution
smbclient -L ip_addr/hostname show remote shares of a windows host
smbget -Rr smb://ip_addr/share like wget can download files from a host windows via smb
mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/share mount a windows network share

IPTABLES (firewall)
iptables -t filter -L show all chains of filtering table
iptables -t nat -L show all chains of nat table
iptables -t filter -F clear all rules from filtering table
iptables -t nat -F clear all rules from table nat
iptables -t filter -X delete any chains created by user
iptables -t filter -A INPUT -p tcp --dport telnet -j ACCEPT allow telnet connections to input
iptables -t filter -A OUTPUT -p tcp --dport http -j DROP block HTTP connections to output
iptables -t filter -A FORWARD -p tcp --dport pop3 -j ACCEPT allow POP3 connections to forward chain
iptables -t filter -A INPUT -j LOG --log-prefix "DROP INPUT" logging sulla chain di input Logging on chain input
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE configure a PAT (Port Address Traslation) on eth0 masking outbound packets
iptables -t nat -A PREROUTING -d 192.168.0.1 -p tcp -m tcp --dport 22 -j DNAT --to-destination 10.0.0.2:22 redirect packets addressed to a host to another host

Monitoring and debugging
top display linux tasks using most cpu
ps -eafw displays linux tasks
ps -e -o pid,args --forest displays linux tasks in a hierarchical mode
pstree Shows a tree system processes
kill -9 ID_Processo force closure of the process and finish it
kill -1 ID_Processo force a process to reload configuration
lsof -p $$ display a list of files opened by processes
lsof /home/user1 displays a list of open files in a given path system
strace -c ls >/dev/null display system calls made and received by a process
strace -f -e open ls >/dev/null display library calls
watch -n1 'cat /proc/interrupts' display interrupts in real-time
last reboot show history reboot
lsmod display kernel loaded
free -m displays status of RAM in megabytes
smartctl -A /dev/hda monitoring reliability of a hard-disk through SMART
smartctl -i /dev/hda check if SMART is active on a hard-disk
tail /var/log/dmesg show events inherent to the process of booting kernel
tail /var/log/messages show system events

Others useful commands
apropos ...keyword display a list of commands that pertain to keywords of a program , useful when you know what your program does, but you don't know the name of the command
man ping display the on-line manual pages for example on ping command - use '-k' option to find any related commands
whatis ...keyword displays description of what a program does
mkbootdisk --device /dev/fd0 `uname -r` create a boot floppy
gpg -c file1 encrypt a file with GNU Privacy Guard
gpg file1.gpg decrypt a file with GNU Privacy Guard
wget -r www.example.com download an entire web site
wget -c www.example.com/file.iso download a file with the ability to stop the download and resume later
echo 'wget -c www.example.com/files.iso' | at 09:00 start a download at any given time
ldd /usr/bin/ssh show shared libraries required by ssh program
alias hh='history' set an alias for a command - hh = history
chsh change shell command
chsh --list-shells nice command to know if you have to remote into another box
who -a show who is logged on, and print: time of last system boot, dead processes, system login processes, active processes spawned by init, current runlevel, last system clock change