FreeKB - Linux Commands articles
Linux Commands articles

Commands$? (return code)alias (create commands)apt-cache (search for a package)apt-get (install update packages)arp (address resolution protocol)at (schedule a one time job)awkbase64 commandbasenamebatch (schedule jobs)bunzip2 (unzip a bzip2 archive)bzip2 (compress file)cat or tac (view the content of a file)chage (user account aging information expire password)chkconfig (runlevel)chmod (change a file or directory standard permissions)chown (change ownership)cp (copy)cpio (create, view, and extract an archive)crontab (schedule reoccurring jobs)curl (DELETE)curl (POST -d --data)curl - -u --user (authentication)curl -k --insecure (ignore SSL certificate warning)curl -o --output (download file)curl -o /dev/null (suppress response body output)curl -S --show-errorcurl -s --silent (hide progress bar)curl -T --upload-filecurl -w --write-out "%{http_code}"curl -X or --request GETcurl 302 (redirect)curl HTTP headers (--head -I)cutdatedebugfs command (recover a deleted file)declare commanddf (disk filesystem usage)df command (inodes)dhclient (dhcp - obtain, renew, and release IP address)diff command (differences between files)dig (view DNS information)du (disk usage)echo (print output)edquota (edit quota)evalexec (execute a command)expand (replace tabs with spaces)Extract a Java archive using the JAR command in Linuxfdisk (format disk partition)file commandfindfind command - date accessed (-atime)find command - date changed (-ctime)find command - date modified (-mtime)find command - exclude "permission denied"find command - exclude directories from search (-not -path)find command - hidden files and directoriesfind files owned by groupfind files owned by userfind files that match permissionfold (wrap text)free (view RAM memory)ftpfuser (determine the PID of a file)fuser (view kill processes)gdisk (format disk partition)genkey (create a public / private key pair using crypto-utils)getent (view entries)getfacl (view access control entries)gpasswd (change group password)gpg (create a public / private key pair)grepgrep (--exclude-dir)groupadd (create group)groupmod (modify group)growisofs (burn CD or DVD)gunzip (unzip a gzip archive)gzip (compress file)hash commandhistoryhostnamehwclock (hardware clock)iconv (character encoding standard)id commandifconfig (IP address information)ifconfig command (temporarily change the MAC address)ifconfig promisc (promiscuous mode)info (information about a command)insmod (insert a module)ipip neighborhood (view address resolution cache)join (combine or merge lines in two different files)journalctl (view the journal)journalctl --since and --until filterskill (end a process)killall (end a process)last (view current and recently logged in users)ldd (shared libraries)linux ks (KickStart installation)ln (hard soft symbolic symlink links)locale (language, country, character encoding standard)logger (add records to a log file)lp (print a file)lpc (list printers)lpq (print queue)lpr (print a file)lprm (remove print jobs)lpstat (list available printers)ls (list)ls (list) --ignorelsblk command (list hard drive solid state drive)lsmod (list loaded modules)lsof commandmail (create send and read emails)mailscript (create send and read emails)mailx (create send and read emails)man (view manual for a command)mkdir (make directory)mke2fs (create a file system)mkfs (create a file system)modinfo (view module information)modprobe (insert and remove modules)mount (mount a partition or share)mv (move)netstat (view network connections)nice (influence a process to run with higher or lower priority)nl (number lines)nmcli connection shownmcli general statusnmcli hostnamenmcli modifynohup command (run a process while logged out)nslookup (name server looking DNS)ntpdate (synchronize to an NTP server)ntpq (view NTP servers being used)parted (format disk partition)passwd (change a users password)paste (read, delimit, combine files)pr (format file for printing)printf (print output)ps (process PID)ps commad - show processes being run by a certain user (-U)ps command - add additional columns (-f)ps command - display a process associated with a certain PID (-p)ps command - display how long a process has been running (-o etime etimes)ps command - show all running processes (-e -A ax)ps command - show processes being run by a system service (-C)pvcreate (create an LVM physical volume)pvdisplay (LVM physical volumes)pvresize command (resize an LVM physical volume)quotacheck command (check disk quota)quotaon (enable quota)read (prompt user input)renice (influence a process to run with higher or lower priority)repquota command (view quota)Resize an LVM logical volume using the LVRESIZE commandrestoreconrm (remove delete)rmdir (remove directory)route (view and create network routes)rpm (view, install, and update Red Hat packages)rpm2cpio command (compress an RPM package into a CPIO archive)sar command (sysstat CPU statistics)scp (transfer files using secure copy protocol)sed (delete)sed (replace string)sendmail (create send and read emails)seq (sequence of numbers)service commandsetfacl (create update access control entries)shutdown (shutdown, reboot, halt, poweroff)sortsource (export variable)split (divide a single file into multiple files)ssh-copy-idssh-keyscan command (get public certificates)star (create, view, extract an archive)stat (atime mtime ctime)su (switch user)sudosudo (give a group permission to run certain commands)sudo (give a user permission to run certain commands)systemctl commandtar (append to an archive)tar (create an archive)tar (delete from an archive)tar (extract an archive)tar (random tips)tar (view an archive)tcpdump commandtee (redirect output to both the console and a file)testtimedatectltop (view processes in real time)touch (create file)tr (trade, replace, change characters)tracepath (trace route to a host)traceroutetzselect (time zone select)ulimitumask (view and update default permission masks)umount (unmount a partition or share)uname (display information about the kernel)unexpand (replace spaces with tabs in a file)uniq (list unique lines in a file)unlinkunset (undefine a variable)unzipuptimeuseradd (create a user account)userdel (delete user account)usermod (modifying a users account)View and create a Java archive using the JAR command in Linuxw (view logged in users)wall (send message to other systems)wc (count words, characters, and lines)wget (download files from remote systems)which commandwho (view logged in users)xargs (convert stdin to an argument)xml_grep (parse XML file)xwininfo command (display information about a window)yum (download, install, remove, update packages)yum clean (/var/yum/cache)yum erase (uninstall a package)yum info (display information about a package)yum install (install a package)yum list (list installed and available packages)yum provides (determine the package that provides a file)yum remove (uninstall a package)yum search (display information about a package)yum update (update a package)yumdownloader (download a package)zipTroubleshootingResolve "not allowed to run sudo"