1. The shell reads a command line from the terminal.
   
2. It creates a child process with fork().
   
3. The child process uses exec() to call in the command from a file.
   
4. Meanwhile, the parent shell uses wait() to wait for the child (command) process to terminate by calling exit.
   
5. The parent shell goes back to step 1.
   

• MISC
  
• Basic Usage
  
• Advanced Usage
  
  
• at
  
• awk
  
• crontab
  
• cut
  
• date
  
• emacs
  
• find
  
• grep
  
• gzip / bzip
  
• host
  
• ident
  
• ln
  
• lp
  
• lpr
  
• ls
  
• nslookup
  
• pr
  
• sed
  
• stty
  
• tar
  
• umask
  

• minicom
  
• rpm
  

awk  - pattern scanning and text processing language
cut  - remove sections from each line of files
tr   - translate or delete characters
uniq - remove duplicate lines from a sorted file
wc   - print the number of newlines, words, and bytes in files
sed  - is a stream editor. A stream editor is used to perform basic text
       transformations on an input stream (a file or input from  a  pipeline).
       while  in  some  ways similar to an editor which permits scripted edits
       (such as ed), sed works by making only one pass over the input(s), and
       is consequently more efficient. But it is sed's ability to filter text
       in a pipeline which particularly distinguishes it from other types of
       editors.

tail:
	tty|tail -c2
		1

awk:
	ls -ld /home/* | grep drwxr-x | awk '{print $1 "\t" $3}'
	ls -ld /home/* | grep drwxr-x | awk '{print $3}' > open.users &

grep:
	$(grep -v EXPR) opposite behavior (don't print if)
		grep -v "denied"

cut:
	echo hello world | cut -c1
		h
	echo hello world | cut -c1-5
		hello
	df -h | grep /dev/hda1 | cut -c 40-43
		100%
	echo file.txt|cut -d"." -f1
		file
	echo file.txt|cut -d"." -f2
		txt

wc:
	users=$(/bin/netstat -t 2>/dev/null | /bin/grep :22 | /usr/bin/wc -l)


IP=`/sbin/ifconfig "$INT"|awk '/inet addr/ {gsub(".*:","",$2); print $2}'`
IP=$(echo "$INT"|sed -e 's/^[^:]*://' -e 's/[ ].*//')
PPPIP=`/sbin/ifconfig $PPPIF|awk '/inet addr/ {gsub(".*:","",$2); print $2}'`
PPPPE=`/sbin/ifconfig $PPPIF|awk '/inet addr/ {gsub(".*:","",$3); print $3}'`
PPPMA=`/sbin/ifconfig $PPPIF|awk '/inet addr/ {gsub(".*:","",$4); print $4}'`
PPPRX=`/sbin/ifconfig $PPPIF|awk '/RX packet/ {gsub(".*:","",$2); print $2}'`
PPPTX=`/sbin/ifconfig $PPPIF|awk '/TX packet/ {gsub(".*:","",$2); print $2}'`


--------------------------------------------------------------------------------

NAME
       cut - remove sections from each line of files

SYNOPSIS
       cut [OPTION]... [FILE]...

DESCRIPTION
       Print selected parts of lines from each FILE to standard output.

       Mandatory  arguments  to  long  options are mandatory for short options
       too.

       -b, --bytes=LIST
              output only these bytes

       -c, --characters=LIST
              output only these characters

       -d, --delimiter=DELIM
              use DELIM instead of TAB for field delimiter

       -f, --fields=LIST
              output only these fields; also print any line that contains no
              delimiter character, unless the -s option is specified

       -n     (ignored)

       -s, --only-delimited
              do not print lines not containing delimiters

--------------------------------------------------------------------------------

NAME
       wc - print the number of newlines, words, and bytes in files

SYNOPSIS
       wc [OPTION]... [FILE]...

DESCRIPTION
       Print newline, word, and byte counts for each FILE, and a total line if
       more than one FILE is specified.  With no FILE, or when FILE is -, read
       standard input.

       -c, --bytes
              print the byte counts

       -m, --chars
              print the character counts

       -l, --lines
              print the newline counts

       -L, --max-line-length
              print the length of the longest line

       -w, --words
              print the word counts