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