Before a command is executed, its input and output may be redirected using a special notation interpreted
by  the  shell.   Redirection  may  also  be used to open and close files for the current shell execution
environment.  The following redirection operators may precede or appear anywhere within a simple  command
or may follow a command.  Redirections are processed in the order they appear, from left to right.

Here Documents
    This type of redirection instructs the shell  to  read  input  from  the  current  source  until  a  line
    containing  only delimiter (with no trailing blanks) is seen.  All of the lines read up to that point are
    then used as the standard input for a command.

    The format of here-documents is:

           <<[-]word
                   here-document
           delimiter

    No parameter expansion, command substitution, arithmetic expansion, or pathname expansion is performed on
    word.   If  any  characters in word are quoted, the delimiter is the result of quote removal on word, and
    the lines in the here-document are not expanded.  If word is unquoted, all lines of the here-document are
    subjected  to  parameter  expansion, command substitution, and arithmetic expansion.  In the latter case,
    the character sequence \<newline> is ignored, and \ must be used to quote the characters \, $, and `.

    If the redirection operator is <<-, then all leading tab characters are stripped from input lines and the
    line  containing  delimiter.  This allows here-documents within shell scripts to be indented in a natural
    fashion.

Here Strings
    A variant of here documents, the format is:

           <<<word

    The word is expanded and supplied to the command on its standard input.

System tray for KDE3/GNOME2 docklet applications

Commands separated  by  a ; are executed sequentially; the shell waits for each command to terminate in turn.  The
return status is the exit status of the last command executed.

stream editor for filtering and transforming text

-i[SUFFIX], --in-place[=SUFFIX]

       edit files in place (makes backup if extension supplied)

-e script, --expression=script

       add the script to the commands to be executed

If no -e, --expression, -f, or --file option is given, then the first non-option argument is taken as the
sed script to interpret.  All remaining arguments are names  of  input  files;  if  no  input  files  are
specified, then the standard input is read.

display a line of text

-e     enable interpretation of backslash escapes

Echo the STRING(s) to standard output.

Pipelines
    A  pipeline is a sequence of one or more commands separated by one of the control operators | or |&.  The
    format for a pipeline is:

           [time [-p]] [ ! ] command [ [|⎪|&] command2 ... ]

    The standard output of command is connected  via  a  pipe  to  the  standard  input  of  command2.   This
    connection  is performed before any redirections specified by the command (see REDIRECTION below).  If |&
    is used, the standard error of command is connected to command2's standard input through the pipe; it  is
    shorthand  for  2>&1  |.   This  implicit  redirection  of  the  standard  error  is  performed after any
    redirections specified by the command.

    The return status of a pipeline is the exit status of the last command, unless  the  pipefail  option  is
    enabled.   If  pipefail  is  enabled,  the  pipeline's return status is the value of the last (rightmost)
    command to exit with a non-zero status, or zero if all commands exit successfully.  If the reserved  word
    !   precedes  a  pipeline, the exit status of that pipeline is the logical negation of the exit status as
    described above.  The shell waits for all commands in the pipeline to terminate before returning a value.

    If the time reserved word precedes a pipeline, the elapsed as well as user and system  time  consumed  by
    its execution are reported when the pipeline terminates.  The -p option changes the output format to that
    specified by POSIX.  When the shell is in posix mode, it does not recognize time as a  reserved  word  if
    the  next  token begins with a `-'.  The TIMEFORMAT variable may be set to a format string that specifies
    how the timing information should be displayed; see the description of TIMEFORMAT under  Shell  Variables
    below.

    When the shell is in posix mode, time may be followed by a newline.  In this case, the shell displays the
    total user and system time consumed by the shell and its children.  The TIMEFORMAT variable may  be  used
    to specify the format of the time information.

    Each command in a pipeline is executed as a separate process (i.e., in a subshell).

read from standard input and write to standard output and files

Copy standard input to each FILE, and also to standard output.

If a FILE is -, copy again to standard output.

If a command is terminated by the control operator &, the shell executes the command in the background in
a subshell.  The shell does not wait for the command to finish, and the return  status  is  0.

suspend execution for an interval

transfer a URL

-I, --head
       (HTTP/FTP/FILE)  Fetch the HTTP-header only! HTTP-servers feature the command HEAD which this uses
       to get nothing but the header of a document. When used on a FTP or FILE file,  curl  displays  the
       file size and last modification time only.

change the working directory

directory
       An absolute or relative pathname of the directory that shall become the new working directory. The
       interpretation of a relative pathname by cd depends on the  -L  option  and  the  CDPATH  and  PWD
       environment variables. If directory is an empty string, the results are unspecified.

-      When a hyphen is used as the operand, this shall be equivalent to the command:

       cd "$OLDPWD" && pwd

which changes to the previous working directory and then writes its name.