sed(1) -n '/\.ph\(p\|tml\)$/p' \ | sort.1posix -u | xargs(1) ls.1posix -f1 -- 2>/dev/null
stream editor for filtering and transforming text
-n, --quiet, --silent

       suppress automatic printing of pattern space
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.
    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

    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).
sort, merge, or sequence check text files
-u     Unique: suppress all but one in each set of lines having equal keys.  If used with the -c  option,
       check  that there are no lines with duplicate keys, in addition to checking that the input file is

The following options shall override the default ordering rules. When ordering options appear independent
of any key field specifications, the requested field ordering rules shall be applied globally to all sort
keys. When attached to a specific key (see -k), the specified ordering options shall override all  global
ordering options for that key.
build and execute command lines from standard input
list directory contents
-f     Force each argument to be interpreted as a directory and list the name found in  each  slot.  This
       option  shall  turn  off -l, -t, -s, and -r, and shall turn on -a; the order is the order in which
       entries appear in the directory.
-1     (The numeric digit one.) Force output to be one entry per line.
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.

Redirecting Output
    Redirection of output causes the file whose name results from the expansion of  word  to  be  opened  for
    writing  on  file descriptor n, or the standard output (file descriptor 1) if n is not specified.  If the
    file does not exist it is created; if it does exist it is truncated to zero size.

    The general format for redirecting output is:


    If the redirection operator is >, and the noclobber option to the  set  builtin  has  been  enabled,  the
    redirection  will  fail if the file whose name results from the expansion of word exists and is a regular
    file.  If the redirection operator is >|, or the redirection operator is > and the  noclobber  option  to
    the  set  builtin  command  is  not  enabled, the redirection is attempted even if the file named by word
source manpages: sedsortxargsls