Linux Command Line in English
来源:互联网 发布:冒险岛v矩阵 编辑:程序博客网 时间:2024/05/22 14:33
System information
CommandDescription# archshow architecture of machine(1) [man]# cal 2007show the timetable of 2007 [man]# cat /proc/cpuinfoshow information CPU info [man]# cat /proc/interruptsshow interrupts [man]# cat /proc/meminfoverify memory use [man]# cat /proc/swapsshow file(s) swap [man]# cat /proc/versionshow version of the kernel [man]# cat /proc/net/devshow network adpters and statistics [man]# cat /proc/mountsshow mounted file system(s) [man]# clock -wsave date changes on BIOS [man]# dateshow system date [man]# date 041217002007.00set date and time - MonthDayhoursMinutesYear.Seconds [man]# dmidecode -qshow hardware system components - (SMBIOS / DMI) [man]# hdparm -i /dev/hdadisplays the characteristics of a hard-disk [man]# hdparm -tT /dev/sdaperform test reading on a hard-disk [man]# lspci -tvdisplay PCI devices [man]# lsusb -tvshow USB devices [man]# uname -mshow architecture of machine(2) [man]# uname -rshow used kernel version [man] « TOP « Shutdown, Restart and Logout of a system
CommandDescription# init 0shutdown system(2) [man]# logoutleaving session [man]# rebootreboot(2) [man]# shutdown -h nowshutdown system(1) [man]# shutdown -h 16:30 &planned shutdown of the system at 16:30 [man]# shutdown -ccancel a planned shutdown of the system [man]# shutdown -r nowreboot(1) [man]# telinit 0shutdown system(3) [man] « TOP « Files and Directory
CommandDescription# cd /homeenter to directory '/ home' [man]# cd ..go back one level [man]# cd ../..go back two levels [man]# cdgo to home directory [man]# cd ~user1go to home directory [man]# cd -go to previous directory [man]# cp file1 file2copying a file [man]# cp dir/* .copy all files of a directory within the current work directory [man]# cp -a /tmp/dir1 .copy a directory within the current work directory [man]# cp -a dir1 dir2copy a directory [man]# cp file file1outputs the mime type of the file as text [man]# iconv -llists known encodings [man]# iconv -f fromEncoding -t toEncoding inputFile > outputFileconverting the coding of characters from one format to another [man]# find . -maxdepth 1 -name *.jpg -print -exec convertbatch resize files in the current directory and send them to a thumbnails directory (requires convert from Imagemagick) [man]# ln -s file1 lnk1create a symbolic link to file or directory [man]# ln file1 lnk1create a physical link to file or directory [man]# lsview files of directory [man]# ls -Fview files of directory [man]# ls -lshow details of files and directory [man]# ls -ashow hidden files [man]# ls *[0-9]*show files and directory containing numbers [man]# lstreeshow files and directories in a tree starting from root(2) [man]# mkdir dir1create a directory called 'dir1' [man]# mkdir dir1 dir2create two directories simultaneously [man]# mkdir -p /tmp/dir1/dir2create a directory tree [man]# mv dir1 new_dirrename / move a file or directory [man]# pwdshow the path of work directory [man]# rm -f file1delete file called 'file1' [man]# rm -rf dir1remove a directory called 'dir1' and contents recursively [man]# rm -rf dir1 dir2remove two directories and their contents recursively [man]# rmdir dir1delete directory called 'dir1' [man]# touch -t 0712250000 file1modify timestamp of a file or directory - (YYMMDDhhmm) [man]# treeshow files and directories in a tree starting from root(1) [man] « TOP « File search
CommandDescription# find / -name file1search file and directory into root filesystem from '/' [man]# find / -user user1search files and directories belonging to 'user1' [man]# find /home/user1 -name /*.binsearch files with '. bin' extension within directory '/ home/user1' [man]# find /usr/bin -type f -atime +100search binary files are not used in the last 100 days [man]# find /usr/bin -type f -mtime -10search files created or changed within 10 days [man]# find / -name *.rpm -exec chmod 755 '{}' /;search files with '.rpm' extension and modify permits [man]# find / -xdev -name /*.rpmsearch files with '.rpm' extension ignoring removable partitions as cdrom, pen-drive, etc.… [man]# locate /*.psfind files with the '.ps' extension - first run 'updatedb' command [man]# whereis haltshow location of a binary file, source or man [man]# which haltshow full path to a binary / executable [man] « TOP « Mounting a Filesystem
CommandDescription# fuser -km /mnt/hda2force umount when the device is busy [man]# mount /dev/hda2 /mnt/hda2mount disk called hda2 - verify existence of the directory '/ mnt/hda2' [man]# mount /dev/fd0 /mnt/floppymount a floppy disk [man]# mount /dev/cdrom /mnt/cdrommount a cdrom / dvdrom [man]# mount /dev/hdc /mnt/cdrecordermount a cdrw / dvdrom [man]# mount /dev/hdb /mnt/cdrecordermount a cdrw / dvdrom [man]# mount -o loop file.iso /mnt/cdrommount a file or iso image [man]# mount -t vfat /dev/hda5 /mnt/hda5mount a Windows FAT32 file system [man]# mount /dev/sda1 /mnt/usbdiskmount a usb pen-drive or flash-drive [man]# mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/sharemount a windows network share [man]# umount /dev/hda2unmount disk called hda2 - exit from mount point '/ mnt/hda2' first [man]# umount -n /mnt/hda2run umount without writing the file /etc/mtab - useful when the file is read-only or the hard disk is full [man] « TOP « Disk Space
CommandDescription# df -hshow list of partitions mounted [man]# dpkg-query -W -f='${Installed-Size;10}t${Package}n' | sort -k1,1nshow the used space by installed deb packages, sorting by size (debian, ubuntu and alike) [man]# du -sh dir1estimate space used by directory 'dir1' [man]# du -sk * | sort -rnshow size of the files and directories sorted by size [man]# ls -lSr |moreshow size of the files and directories ordered by size [man]# rpm -q -a --qf '%10{SIZE}t%{NAME}n' | sort -k1,1nshow the used space by rpm packages installed sorted by size (fedora, redhat and alike) [man] « TOP « Users and Groups
CommandDescription# chage -E 2005-12-31 user1set deadline for user password [man]# groupadd [group]create a new group [man]# groupdel [group]delete a group [man]# groupmod -n moon sunrename a group from moon to sun [man]# grpckcheck correct syntax and file format of '/etc/group' and groups existence [man]# newgrp - [group]log into a new group to change default group of newly created files [man]# passwdchange password [man]# passwd user1change a user password (only by root) [man]# pwckcheck correct syntax and file format of '/etc/passwd' and users existence [man]# useradd -c "User Linux" -g admin -d /home/user1 -s /bin/bash user1create a new user "user1" belongs "admin" group [man]# useradd user1create a new user [man]# userdel -r user1delete a user ( '-r' eliminates home directory) [man]# usermod -c "User FTP" -g system -d /ftp/user1 -s /bin/nologin user1change user attributes as description, group and other [man] « TOP « Permits on Files
CommandDescription# chgrp group1 file1change group of files [man]# chmod ugo+rwx directory1set permissions reading (r), write (w) and (x) access to users owner (u) group (g) and others (o) [man]# chmod go-rwx directory1remove permits reading (r), write (w) and (x) access to users group (g) and others (or [man]# chmod u+s /bin/file1set SUID bit on a binary file - the user that running that file gets same privileges as owner [man]# chmod u-s /bin/file1disable SUID bit on a binary file [man]# chmod g+s /home/publicset SGID bit on a directory - similar to SUID but for directory [man]# chmod g-s /home/publicdisable SGID bit on a directory [man]# chmod o+t /home/publicset STIKY bit on a directory - allows files deletion only to legitimate owners [man]# chmod o-t /home/publicdisable STIKY bit on a directory [man]# chown user1 file1change owner of a file [man]# chown -R user1 directory1change user owner of a directory and all the files and directories contained inside [man]# chown user1:group1 file1change user and group ownership of a file [man]# find / -perm -u+sview all files on the system with SUID configured [man]# ls -lhshow permits on files [man]# ls /tmp | pr -T5 -W$COLUMNSdivide terminal into 5 columns [man] « TOP « Special Attributes on files
CommandDescription# chattr +a file1allows write opening of a file only append mode [man]# chattr +c file1allows that a file is compressed / decompressed automatically by the kernel [man]# chattr +d file1makes sure that the program ignores Dump the files during backup [man]# chattr +i file1makes it an immutable file, which can not be removed, altered, renamed or linked [man]# chattr +s file1allows a file to be deleted safely [man]# chattr +S file1makes sure that if a file is modified changes are written in synchronous mode as with sync [man]# chattr +u file1allows you to recover the contents of a file even if it is canceled [man]# lsattrshow specials attributes [man] « TOP « Archives and compressed files
CommandDescription# bunzip2 file1.bz2decompress a file called 'file1.bz2' [man]# bzip2 file1compress a file called 'file1' [man]# gunzip file1.gzdecompress a file called 'file1.gz' [man]# gzip file1compress a file called 'file1' [man]# gzip -9 file1compress with maximum compression [man]# rar a file1.rar test_filecreate an archive rar called 'file1.rar' [man]# rar a file1.rar file1 file2 dir1compress 'file1', 'file2' and 'dir1' simultaneously [man]# rar x file1.rardecompress rar archive [man]# tar -cvf archive.tar file1create a uncompressed tarball [man]# tar -cvf archive.tar file1 file2 dir1create an archive containing 'file1', 'file2' and 'dir1' [man]# tar -tf archive.tarshow contents of an archive [man]# tar -xvf archive.tarextract a tarball [man]# tar -xvf archive.tar -C /tmpextract a tarball into / tmp [man]# tar -cvfj archive.tar.bz2 dir1create a tarball compressed into bzip2 [man]# tar -xvfj archive.tar.bz2decompress a compressed tar archive in bzip2 [man]# tar -cvfz archive.tar.gz dir1create a tarball compressed into gzip [man]# tar -xvfz archive.tar.gzdecompress a compressed tar archive in gzip [man]# unrar x file1.rardecompress rar archive [man]# unzip file1.zipdecompress a zip archive [man]# zip file1.zip file1create an archive compressed in zip [man]# zip -r file1.zip file1 file2 dir1compress in zip several files and directories simultaneously [man] « TOP « RPM Packages ( Fedora, Red Hat and like)
CommandDescription# rpm -ivh [package.rpm]install a rpm package [man]# rpm -ivh --nodeeps [package.rpm]install a rpm package ignoring dependencies requests [man]# rpm -U [package.rpm]upgrade a rpm package without changing configuration files [man]# rpm -F [package.rpm]upgrade a rpm package only if it is already installed [man]# rpm -e [package]remove a rpm package [man]# rpm -qashow all rpm packages installed on the system [man]# rpm -qa | grep httpdshow all rpm packages with the name "httpd" [man]# rpm -qi [package]obtain information on a specific package installed [man]# rpm -qg "System Environment/Daemons"show rpm packages of a group software [man]# rpm -ql [package]show list of files provided by a rpm package installed [man]# rpm -qc [package]show list of configuration files provided by a rpm package installed [man]# rpm -q [package] --whatrequiresshow list of dependencies required for a rpm packet [man]# rpm -q [package] --whatprovidesshow capability provided by a rpm package [man]# rpm -q [package] --scriptsshow scripts started during installation / removal [man]# rpm -q [package] --changelogshow history of revisions of a rpm package [man]# rpm -qf /etc/httpd/conf/httpd.confverify which rpm package belongs to a given file [man]# rpm -qp [package.rpm] -lshow list of files provided by a rpm package not yet installed [man]# rpm --import /media/cdrom/RPM-GPG-KEYimport public-key digital signature [man]# rpm --checksig [package.rpm]verify the integrity of a rpm package [man]# rpm -qa gpg-pubkeyverify integrity of all rpm packages installed [man]# rpm -V [package]check file size, permissions, type, owner, group, MD5 checksum and last modification [man]# rpm -Vacheck all rpm packages installed on the system - use with caution [man]# rpm -Vp [package.rpm]verify a rpm package not yet installed [man]# rpm -ivh /usr/src/redhat/RPMS/`arch`/[package.rpm]install a package built from a rpm source [man]# rpm2cpio [package.rpm] | cpio --extract --make-directories *bin*extract executable file from a rpm package [man]# rpmbuild --rebuild [package.src.rpm]build a rpm package from a rpm source [man] « TOP « YUM packages tool (Fedora, RedHat and alike)
CommandDescription# yum -y install [package]download and install a rpm package [man]# yum localinstall [package.rpm]That will install an RPM, and try to resolve all the dependencies for you using your repositories. [man]# yum -y updateupdate all rpm packages installed on the system [man]# yum update [package]upgrade a rpm package [man]# yum remove [package]remove a rpm package [man]# yum listlist all packages installed on the system [man]# yum search [package]find a package on rpm repository [man]# yum clean [package]clean up rpm cache erasing downloaded packages [man]# yum clean headersremove all files headers that the system uses to resolve dependency [man]# yum clean allremove from the cache packages and headers files [man] « TOP « DEB packages (Debian, Ubuntu and like)
CommandDescription# dpkg -i [package.deb]install / upgrade a deb package [man]# dpkg -r [package]remove a deb package from the system [man]# dpkg -lshow all deb packages installed on the system [man]# dpkg -l | grep httpdshow all deb packages with the name "httpd" [man]# dpkg -s [package]obtain information on a specific package installed on system [man]# dpkg -L [package]show list of files provided by a package installed on system [man]# dpkg --contents [package.deb]show list of files provided by a package not yet installed [man]# dpkg -S /bin/pingverify which package belongs to a given file [man] « TOP « APT packages tool (Debian, Ubuntu and alike)
CommandDescription# apt-cache search [package]returns list of packages which corresponds string "searched-packages" [man]# apt-cdrom install [package]install / upgrade a deb package from cdrom [man]# apt-get install [package]install / upgrade a deb package [man]# apt-get updateupdate the package list [man]# apt-get upgradeupgrade all of the installed packages [man]# apt-get remove [package]remove a deb package from system [man]# apt-get checkverify correct resolution of dependencies [man]# apt-get cleanclean up cache from packages downloaded [man] « TOP « Pacman packages tool (Arch, Frugalware and alike)
CommandDescription# pacman -S nameInstall package 'name' with dependencies [man]# pacman -R nameDelete package 'name' and all files of it [man] « TOP « View file content
CommandDescription# cat file1view the contents of a file starting from the first row [man]# head -2 file1view first two lines of a file [man]# less file1similar to 'more' command but which allows backward movement in the file as well as forward movement [man]# more file1view content of a file along [man]# tac file1view the contents of a file starting from the last line [man]# tail -2 file1view last two lines of a file [man]# tail -f /var/log/messagesview in real time what is added to a file [man] « TOP « Text Manipulation
CommandDescription# cat example.txt | awk 'NR%2==1'remove all even lines from example.txt [man]# echo a b c | awk '{print $1}'view the first column of a line [man]# echo a b c | awk '{print $1,$3}'view the first and third column of a line [man]# cat -n file1number row of a file [man]# comm -1 file1 file2compare contents of two files by deleting only unique lines from 'file1' [man]# comm -2 file1 file2compare contents of two files by deleting only unique lines from 'file2' [man]# comm -3 file1 file2compare contents of two files by deleting only the lines that appear on both files [man]# diff file1 file2find differences between two files [man]# grep Aug /var/log/messageslook up words "Aug" on file '/var/log/messages' [man]# grep ^Aug /var/log/messageslook up words that begin with "Aug" on file '/var/log/messages' [man]# grep [0-9] /var/log/messagesselect from file '/var/log/messages' all lines that contain numbers [man]# grep Aug -R /var/log/*search string "Aug" at directory '/var/log' and below [man]# paste file1 file2merging contents of two files for columns [man]# paste -d '+' file1 file2merging contents of two files for columns with '+' delimiter on the center [man]# sdiff file1 file2find differences between two files and merge interactively alike "diff" [man]# sed 's/string1/string2/g' example.txtreplace "string1" with "string2" in example.txt [man]# sed '/^$/d' example.txtremove all blank lines from example.txt [man]# sed '/ *#/d; /^$/d' example.txtremove comments and blank lines from example.txt [man]# sed -e '1d' exampe.txteliminates the first line from file example.txt [man]# sed -n '/string1/p'view only lines that contain the word "string1" [man]# sed -e 's/ *$//' example.txtremove empty characters at the end of each row [man]# sed -e 's/string1//g' example.txtremove only the word "string1" from text and leave intact all [man]# sed -n '1,5p' example.txtprint from 1th to 5th row of example.txt [man]# sed -n '5p;5q' example.txtprint row number 5 of example.txt [man]# sed -e 's/00*/0/g' example.txtreplace more zeros with a single zero [man]# sort file1 file2sort contents of two files [man]# sort file1 file2 | uniqsort contents of two files omitting lines repeated [man]# sort file1 file2 | uniq -usort contents of two files by viewing only unique line [man]# sort file1 file2 | uniq -dsort contents of two files by viewing only duplicate line [man]# echo 'word' | tr '[:lower:]' '[:upper:]'convert from lower case in upper case [man] « TOP « Character set and Format file conversion
CommandDescription# dos2unix filedos.txt fileunix.txtconvert a text file format from MSDOS to UNIX [man]# recode ..HTML < page.txt > page.htmlconvert a text file to html [man]# recode -l | moreshow all available formats conversion [man]# unix2dos fileunix.txt filedos.txtconvert a text file format from UNIX to MSDOS [man] « TOP « Filesystem Analysis
CommandDescription# badblocks -v /dev/hda1check bad blocks on disk hda1 [man]# dosfsck /dev/hda1repair / check integrity of dos filesystems on disk hda1 [man]# e2fsck /dev/hda1repair / check integrity of ext2 filesystem on disk hda1 [man]# e2fsck -j /dev/hda1repair / check integrity of ext3 filesystem on disk hda1 [man]# fsck /dev/hda1repair / check integrity of linux filesystem on disk hda1 [man]# fsck.ext2 /dev/hda1repair / check integrity of ext2 filesystem on disk hda1 [man]# fsck.ext3 /dev/hda1repair / check integrity of ext3 filesystem on disk hda1 [man]# fsck.vfat /dev/hda1repair / check integrity of fat filesystem on disk hda1 [man]# fsck.msdos /dev/hda1repair / check integrity of dos filesystem on disk hda1 [man] « TOP « Format a Filesystem
CommandDescription# fdformat -n /dev/fd0format a floppy disk [man]# mke2fs /dev/hda1create a filesystem type linux ext2 on hda1 partition [man]# mke2fs -j /dev/hda1create a filesystem type linux ext3 (journal) on hda1 partition [man]# mkfs /dev/hda1create a filesystem type linux on hda1 partition [man]# mkfs -t vfat 32 -F /dev/hda1create a FAT32 filesystem [man]# mkswap /dev/hda3create a swap filesystem [man] « TOP « Filesystem SWAP
CommandDescription# mkswap /dev/hda3create a swap filesystem [man]# swapon /dev/hda3activating a new swap partition [man]# swapon /dev/hda2 /dev/hdb3activate two swap partitions [man] « TOP « Backup
CommandDescription# find /var/log -name '*.log' | tar cv --files-from=- | bzip2 > log.tar.bz2find all files with '.log' extention and make an bzip archive [man]# find /home/user1 -name '*.txt' | xargs cp -av --target-directory=/home/backup/ --parentsfind and copy all files with '.txt' extention from a directory to another [man]# 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 [man]# dd if=/dev/sda of=/tmp/file1backup content of the harddrive to a file [man]# dd if=/dev/hda of=/dev/fd0 bs=512 count=1make a copy of MBR (Master Boot Record) to floppy [man]# dd if=/dev/fd0 of=/dev/hda bs=512 count=1restore MBR from backup copy saved to floppy [man]# dump -0aj -f /tmp/home0.bak /homemake a full backup of directory '/home' [man]# dump -1aj -f /tmp/home0.bak /homemake a incremental backup of directory '/home' [man]# restore -if /tmp/home0.bakrestoring a backup interactively [man]# rsync -rogpav --delete /home /tmpsynchronization between directories [man]# rsync -rogpav -e ssh --delete /home ip_address:/tmprsync via SSH tunnel [man]# rsync -az -e ssh --delete ip_addr:/home/public /home/localsynchronize a local directory with a remote directory via ssh and compression [man]# rsync -az -e ssh --delete /home/local ip_addr:/home/publicsynchronize a remote directory with a local directory via ssh and compression [man]# tar -Puf backup.tar /home/usermake a incremental backup of directory '/home/user' [man]# ( 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 [man]# ( tar c /home ) | ssh -C user@ip_addr 'cd /home/backup-home && tar x -p'copy a local directory on remote directory via ssh [man]# tar cf - . | (cd /tmp/backup ; tar xf - )local copy preserving permits and links from a directory to another [man] « TOP « CDROM
CommandDescription# cd-paranoia -Brip audio tracks from a CD to wav files [man]# cd-paranoia --rip first three audio tracks from a CD to wav files [man]# cdrecord -v gracetime=2 dev=/dev/cdrom -eject blank=fast -forceclean a rewritable cdrom [man]# cdrecord -v dev=/dev/cdrom cd.isoburn an ISO image [man]# gzip -dc cd_iso.gz | cdrecord dev=/dev/cdrom -burn a compressed ISO image [man]# cdrecord --scanbusscan bus to identify the channel scsi [man]# dd if=/dev/hdc | md5sumperform an md5sum on a device, like a CD [man]# mkisofs /dev/cdrom > cd.isocreate an iso image of cdrom on disk [man]# mkisofs /dev/cdrom | gzip > cd_iso.gzcreate a compressed iso image of cdrom on disk [man]# mkisofs -J -allow-leading-dots -R -Vcreate an iso image of a directory [man]# mount -o loop cd.iso /mnt/isomount an ISO image [man] « TOP « Networking (LAN / WiFi)
CommandDescription# dhclient eth0active interface 'eth0' in dhcp mode [man]# ethtool eth0show network statistics of eth0 [man]# host www.example.comlookup hostname to resolve name to ip address and viceversa [man]# hostnameshow hostname of system [man]# ifconfig eth0show configuration of an ethernet network card [man]# ifconfig eth0 192.168.1.1 netmask 255.255.255.0configure IP Address [man]# ifconfig eth0 promiscconfigure 'eth0' in promiscuous mode to gather packets (sniffing) [man]# ifdown eth0disable an interface 'eth0' [man]# ifup eth0activate an interface 'eth0' [man]# ip link showshow link status of all network interfaces [man]# iwconfig eth1show wireless networks [man]# iwlist scanwifi scanning to display the wireless connections available [man]# mii-tool eth0show link status of 'eth0' [man]# netstat -tupshow all active network connections and their PID [man]# netstat -tuplshow all network services listening on the system and their PID [man]# netstat -rnshow routing table alike "route -n" [man]# nslookup www.example.comlookup hostname to resolve name to ip address and viceversa [man]# route -nshow routing table [man]# route add -net 0/0 gw IP_Gatewayconfigure default gateway [man]# route add -net 192.168.0.0 netmask 255.255.0.0 gw 192.168.1.1configure static route to reach network '192.168.0.0/16' [man]# route del 0/0 gw IP_gatewayremove static route [man]# echo "1" > /proc/sys/net/ipv4/ip_forwardactivate ip routing temporarily [man]# tcpdump tcp port 80show all HTTP traffic [man]# whois www.example.comlookup on Whois database [man] « TOP « Microsoft Windows networks (samba)
CommandDescription# mount -t smbfs -o username=user,password=pass //WinClient/share /mnt/sharemount a windows network share [man]# nbtscan ip_addrnetbios name resolution [man]# nmblookup -A ip_addrnetbios name resolution [man]# smbclient -L ip_addr/hostnameshow remote shares of a windows host [man]# smbget -Rr smb://ip_addr/sharelike wget can download files from a host windows via smb [man] « TOP « IPTABLES (firewall)
CommandDescription# iptables -t filter -Lshow all chains of filtering table [man]# iptables -t nat -Lshow all chains of nat table [man]# iptables -t filter -Fclear all rules from filtering table [man]# iptables -t nat -Fclear all rules from table nat [man]# iptables -t filter -Xdelete any chains created by user [man]# iptables -t filter -A INPUT -p tcp --dport telnet -j ACCEPTallow telnet connections to input [man]# iptables -t filter -A OUTPUT -p tcp --dport http -j DROPblock HTTP connections to output [man]# iptables -t filter -A FORWARD -p tcp --dport pop3 -j ACCEPTallow POP3 connections to forward chain [man]# iptables -t filter -A INPUT -j LOG --log-prefixLogging on input chain [man]# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADEconfigure a PAT (Port Address Traslation) on eth0 masking outbound packets [man]# iptables -t nat -A PREROUTING -d 192.168.0.1 -p tcp -m tcp --dport 22 -j DNAT --to-destination 10.0.0.2:22redirect packets addressed to a host to another host [man] « TOP « Monitoring and debugging
CommandDescription# free -mdisplays status of RAM in megabytes [man]# kill -9 process_idforce closure of the process and finish it [man]# kill -1 process_idforce a process to reload configuration [man]# last rebootshow history reboot [man]# lsmoddisplay kernel loaded [man]# lsof -p process_iddisplay a list of files opened by processes [man]# lsof /home/user1displays a list of open files in a given path system [man]# ps -eafwdisplays linux tasks [man]# ps -e -o pid,args --forestdisplays linux tasks in a hierarchical mode [man]# pstreeShows a tree system processes [man]# smartctl -A /dev/hdamonitoring reliability of a hard-disk through SMART [man]# smartctl -i /dev/hdacheck if SMART is active on a hard-disk [man]# strace -c ls >/dev/nulldisplay system calls made and received by a process [man]# strace -f -e open ls >/dev/nulldisplay library calls [man]# tail /var/log/dmesgshow events inherent to the process of booting kernel [man]# tail /var/log/messagesshow system events [man]# topdisplay linux tasks using most cpu [man]# watch -n1 'cat /proc/interrupts'display interrupts in real-time [man] « TOP « Others useful commands
CommandDescription# alias hh='history'set an alias for a command - hh = history [man]# apropos ...keyworddisplay 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]# chshchange shell command [man]# chsh --list-shellsnice command to know if you have to remote into another box [man]# gpg -c file1encrypt a file with GNU Privacy Guard [man]# gpg file1.gpgdecrypt a file with GNU Privacy Guard [man]# ldd /usr/bin/sshshow shared libraries required by ssh program [man]# man pingdisplay the on-line manual pages for example on ping command - use '-k' option to find any related commands [man]# mkbootdisk --device /dev/fd0 `uname -r`create a boot floppy [man]# wget -r www.example.comdownload an entire web site [man]# wget -c www.example.com/file.isodownload a file with the ability to stop the download and resume later [man]# echo 'wget -c www.example.com/files.iso' | at 09:00start a download at any given time [man]# whatis ...keyworddisplays description of what a program does [man]# who -ashow 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 [man]