Script de ping

[Ricardo Eureka!]

El 23/03/09, eva <evammg en gmail.com> escribió:
>  Me ha encantado la forma de hacer el script, Ricardo, me harias el
>  favor de explicar como funciona? Me encantaria que lo explicaras.
>  la doble barra?, luego corchetes?, una tuberia (eso si lo entiendo),
>  que redirige las salida para &2?
>  desde luego si va bien (cuentanos, pepito!!!), me parece una forma de
>  hacerlo muy elegante y limpia :D

Hmmmm...muchas gracias, pero...nada que una visita por man bash no
pueda enseñarte.

Copio y pego las partes relacionadas, el resto del trabajo, hazlo tu ;)

" An OR list has the form

              command || command2

       command2  is  executed  if  and  only if command returns a
       non-zero exit status.  The return status  of  AND  and  OR
       lists  is  the exit status of the last command executed in
       the list."
....

"       { list; }
              list is simply executed in the current shell  envi-
              ronment.   This  is  known as a group command.  The
              return status is the exit status of list.
"
....

"REDIRECTION
       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 any-
       where  within  a  simple  command or may follow a command.
       Redirections are processed in the order they appear,  from
       left to right.

       In the following descriptions, if the file descriptor num-
       ber is omitted, and the first character of the redirection
       operator  is  <,  the  redirection  refers to the standard
       input (file descriptor 0).  If the first character of  the
       redirection  operator  is >, the redirection refers to the
       standard output (file descriptor 1).

       The word that follows the redirection operator in the fol-
       lowing descriptions is subjected to brace expansion, tilde
       expansion,  parameter  expansion,  command   substitution,
       arithmetic  expansion,  quote removal, and pathname expan-
       sion.  If it expands to more than one word,  bash  reports
       an error.

       Note  that  the order of redirections is significant.  For
       example, the command

              ls > dirlist 2>&1

       directs both standard output and  standard  error  to  the
       file dirlist, while the command

              ls 2>&1 > dirlist

       directs  only the standard output to file dirlist, because
       the standard  error  was  duplicated  as  standard  output
       before the standard output was redirected to dirlist.
"

Hay miles de tutoriales, HOWTOS, manuales, etc del elegante, sencillo
y potente BASH por alli, esperando que lo descubras :D

Suerte y bienvenido!!!!!


-- 
Ricardo A.Frydman
Administrador Senior de Sistemas Unix
Sun Certified System Administrator - Solaris 10
http://unix-argentina.blogspot.com/
http://www.warrenbuffet.com.ar