Linux

Linux Commands

Favorite Commands (Debian/Ubuntu):

Some Notation:
" #": everything following this to the end of the line is a comment...you can also paste it...the shell will ignore it
FILE: filename
DIR: directory
PATH: directory/[file] location
LINE: line's contents
CMD: command like awk, cat, echo, grep, etc.
LIT: literal/static variable no REGEX
REGEX: "REGular EXpression"...a pattern matching expression
DATE: date...format may vary
TIME: time...format may vary
NUM: numeric value
SEP: field separator
VAR: variable
URL: Uniform Resource Locator
/dev/null: a device file representing nothing
read: shell builtin that read's stdin
*: wildcard

• type CMD    # cool builtin that tells you what you are looking at...
• alias
• builtin
• command
• etc.
• uname -a    # lists basic system information
• uptime    # print time since system boot
• top    # traditional performance monitor
• htop    # improved performance monitor
• mytop    # a top like tool for MySQL
• itop    # a top like tool I programmed for Informix 9.40.FC7
• du -hd1 | sort -h    # disk usage (human size), one level deep and sum by directory...pipe to sort smallest to largest
• find . -type f -exec grep -in "LIT/REGEX" {} /dev/null \;    # case insensitive search regular files for "LIT/REGEX" inside file...printing "path/filename:line:content"
• find . -type f -exec ls -hlatr {} \; | sort -hk5,5    # long list all files under a directory, sort smallest to largest (human size)
• find . -maxdepth 1 -type f    # list only regular files in current directory
• rm -rf PATH    # remove a "PATH" and all content
• awk -F'SEP' '{print $NUM}'    # print the column "NUM" delimited by "SEP"
• locate LIT    # print the PATH of file name matching "*LIT*"
• less -S FILE    # page "FILE" with no line wrap
• wget URL    # get "URL" from http/ftp
• scp PATH1 username@hostname:PATH2    # put "PATH1" to "PATH2"
• scp -r PATH1 username@hostname:PATH2    # same as above, but recursively puts directory and all files under it
• scp username@hostname:PATH1 PATH2    # get "PATH1" to "PATH2"
• scp -r username@hostname:PATH1 PATH2    # same as above, but recursively gets directory and all files under it
• cat FILE    # display contents of "FILE"
• vi FILE    # edit/view "FILE"
• echo $VAR    # display contents of variable "VAR"
• >FILE    # zeros out "FILE" keeping current attributes
• cp /dev/null FILE    # zeros out "FILE" keeping current attributes
• touch FILE    # creates a FILE of zero size if does not exist or updates file's timestamp to current time
• \CMD    # unalias "CMD"
• "CMD"    # unalias "CMD"
• while [ 1 ]; do CMD; sleep NUM; done    # repeat CMD with NUM seconds between/wait
• cat FILE | while read LINE; do CMD; done    # read a file line by line doing a CMD until file's end
• apt-get update    # updates the system's package lists
• a2ensite kohlmeyer.us.conf    # Apache...enable a virtual host
• ffmpeg -ss 4.5 -i input.mp3 -t 1.7 output.mp3    # cut a mp3 from 4.5 seconds to 6.2 seconds
• vlc FILE    # play audio or video FILE
• eog FILE    # display image FILE
• gnome-system-monitor    # graphical display of system resources
• gimp    # run GNU Image Manipulation Program