Linux

Favorite Commands:

Some Notation:
FILE: a filename
DIRECTORY: a directory
PATH: a directory/file location
LINE: a line's contents
COMMAND: a command like awk, cat, echo, grep, etc. 
LITERAL: a literal/static variable no REGEX
REGEX: "REGular EXpression"...a pattern matching expression
DATE: a date...format may vary
TIME: a time...format may vary
NUMBER: a numeric value
SEPARATOR: a field separator
VARIABLE: a variable
/dev/null: a device file representing nothing
read: read's stdin

• find . -type f -exec grep -n "LITERAL/REGEX" {} /dev/null \; # search regular files for "LITERAL/REGEX" inside...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'SEPARATOR' '{print $NUMBER}' # print the column "NUMBER" delimited by "SEPARATOR"
• locate LITERAL # print the PATH of file name matching "LITERAL"
• less -S FILE # page "FILE" with no line wrap
• du -hd1 | sort -h # disk usage (human size),one level deep and sum by directory...pipe to sort smallest to largest
• wget PATH # get "PATH" from http/ftp
• scp PATH1 username@hostname:PATH2 # put "PATH1" to "PATH2"
• scp -r PATH1 username@hostname:PATH2 # same as above, but recursively gets directory and all files under it
• scp username@hostname:PATH1 PATH2 # get "PATH1" to "PATH2"
• scp 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 $VARIABLE # display contents of variable "VARIABLE"
• >FILE # zeros out "FILE"
• cp /dev/null FILE # zeros out "FILE"
• \COMMAND # unalias "COMMAND"
• "COMMAND" # unalias "COMMAND"
• while [ 1 ]; do COMMANDS; sleep NUMBER; done # repeat COMMAND with NUMBER seconds between
• cat FILE | while read LINE; do COMMAND; done # read a file line by line doing a COMMAND until file's end

• uname -a # lists basic system information
• uptime # print time since system boot
• apt-get update # updates the system's package lists
• top # traditional performance monitor
• htop # improved performance monitor
• 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