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