Linux command guide
Contents
1. Getting Help
2. Directory Navigation, basic shell tasks, and File Management
3. Redirection and Piping
4. Text Processing
5. Package Management
6. Useful Management Commands
7. Useful Configuration Files
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
2. Directory navigation, basic shell tasks, and File Management
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