Linux Commands
Useful Linux Commands
You can use man [command] to get information about a command, but that is more programmer oriented. You are generally better off going to a search engine and searching for [command] examples.
One of the great powers of Linux is being able to pipe | or redirect outputs from one command to another to do things.
You can also use these commands to create bash scripts.
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Disk Commands
Returns a quick overview of what disks are mounted and how full they are in human readable formatting.
df -h
Directory Commands
Directory details
Returns an estimate of file space usage, in human readable format (k,M,G). Warning: May take a long time.
du -h
Returns a total size of the directories under where this command was run and sorts by size.
du -hsx * | sort -rh | head -10
Create a directory
Creates a directory
md [directory name] mkdir [directory name]
File List
Return a list of files in a directory. This always works (shows file size in bytes)
ls -s
This is a SLES alias of the above
l
Display file size in human-readable values "-h" (K,M,G)
l -h
Sorted by size "S", ascending "r", human-readable "h"
l -Srh
Sorted by time "t", ascending "r", human-readable "h"
l -trh
Show hidden files "a", long list format "l", human-readable "h"
l -alh
File Commands
Show the contents of a file
cat "filename"
Pipe through more to display a screen full of text at a time (space for next page, enter for next line, ctrl-c to break out)
cat "filename" | more
Pipe through less to display file in less.
cat "filename" | less
Find a file
find / -name "fileName"
Find all files with the string "log" as part of the filename.
find . | grep log
Find and recursively unzip all items in a directory structure called zippedDir to the current directory.
find /zippedDir -name "*.zip" -exec unzip {} \;
Find files in current directory older than 7 days and delete them.
find . -mtime +7 -exec rm {} \;
Copy a file
cp origin /destination/file
To copy particular files recursively
cp -r *.txt /destination
To copy to the current directory
cp /software/origin.file .
To secure copy a file to a remote location
scp [source] [destination IP address]:/[destination]
Move a file
Moves file to the destination directory in verbose "v" mode.
mv -v "file" "destination"
Remove or delete a file
Removes a particular file
rm "file"
Removes a directory and its contents
rm -r "directory"
Network
Download the Latest Version of Retain
wget "http://download.gwava.com/download.php?product=Retain&version=current"
Find the IP address of the server
ifconfig
look up mx records
host -t MX [domain.com]
Determine hosts
cat /etc/resolv.conf
DNS
nslookup "Enter" server "Enter"
Trace the route to a server
traceroute [domain.com]
Show the system name
hostname
Secure connect to another system
ssh [hostname or ip address] exit to leave ssh shell
System Commands
Display an overview of the system resources
top
Display memory usage
free -m
