Linux command guide
1. Getting Help
man <command> – Display command help
man find | grep <search string> – Locate specific help text within the manual
info – Provide man help in a different format
cd – Change working directory
cd .. – Change to parent directory
cd ~ – Change to home working directory
pwd – Display working directory
echo <line of text> – Display the line of text (useful for user friendly scripting)
echo $PATH – Display assignment to the environmental variable
time <command> - Time how long <command> took to execute
ls – Lists files in the current working directory
ls -a – Shows hidden files (hidden files start with a dot) as part of file listing
ls -l – Shows file detail
ls –F – Shows File type as part of file listing
history – Records commands typed at command prompt
Ctrl+R to begin a backward search through history
Ctrl+S to search forward through history
Up Arrow and Down Arrow to move a line at a time through history
mkdir ch1 – Creates new directory ch1
mv file1 file2 – Moves file file1 to file2, renames file1 to file2
mv testfile changedfile
less – View file contents page-by-page
unset MYNAME – Removes the environment variable assignment assigned to MYNAME
exit – Terminate shell
cp -R one newone – Copies directory /one recursively to a new directory named /newone
rm etcbackup.tar.gz – Deletes file
3. Redirection and piping
ls > List-of-files.txt – Write list of files in current working directory to the file, List-of-files.txt
pwd >> List-of-files.txt – Append current working directory to the file “List-of-files.txt”
ps ax | grep string – Pipe output of ps ax to grep which searches for string.
4. Text processing commands
cat – Concatenate files together
cat /proc/interrupts – Display information from interrupts file (querying kernel about interrupts)
join – Merge file data from multiple files
sort – Sort file contents
nl – Generate line numbers for each line in a file
tail -20 /var/log/syslog – View last 20 entries posted to syslog file
less – File paging utility
grep string /var/log/* – Search for all occurrences of string in all log files in /var/log directory
5. Package Management
rpm Utility
rpm -q zsh – Check if RPM package zsh (z shell) is installed
rpm -i zsh-4.3.9-4.fc11.i586.rpm – Installs the zsh RPM package
remove zsh: rpm -e zsh – Uninstalls the zsh RPM package
yum Utility
yum install zsh – Downloads and installs zsh package
apt-get Utility
sudo apt-get install alien – Downloads and installs the program “alien”
sudo apt-get install chkconfig – Downloads and installs the program “chkconfig”
sudo apt-get remove package – Remove package
apt-get autoremove – Removes additional programs associated with the main package installation
ldd /bin/ls – Display information about libraries used by the ls program
6. Useful Management Commands
ps aux –
top –
kill pid – Send kill signal to process (pid)
jobs – List all currently running jobs
dmesg | less –
dmesg | grep sdb –
tar -czf BackupFileneme.tar.gz /Folder – Backup a the /Folder and all the files it contains into a single gzipped, tar file (BackupFilename)
tar -xvfz BackupFileneme.tar.gz – Extract the gzipped, tar file (BackupFilename) to some other location on a hard drive
find / -perm +6000 -type f > SUID-GUID-bits-Set.txt – Search system for all SUID/GUID files
7. Useful Configuration Files
Shell Configuration files
Per user configuration files
~/.bashrc
~/.profile
Global configuration files
/etc/bash.bashrc
/etc/profile