linux下的rm rmdir touch pipe commands

jimonitu

               
               
                rm
  rm [options] files
  -d remove directory even if they are not empty.the option is reserved(保留，预定) for privilege users
  -f force removal of write-protected files without prompting
  -i query interactive before removing files
  -r -R if the files is a directory,recursively remove the entire directory and all of its contents,include subdirectories
  the parameter -d ,I can't test success.
rmdir
  rmdir [options] directories
  delete directories ,which must be empty
  -p remove directories and any intervening(插入，干涉，干预) parent directories that become empty as a result.
touch
  touch [options] files
  change the access and/or modification times of files.
  -a change only the access time
  -m change only the modification time
  -t timestamp  ;instead of the current time,use timestamp in the form of [[cc]yy]MMDDhhmm[.ss],for example,the timestamp for january 12,2001,at 6:45 p.m is 200101121845
  
pipes
  this is accomplished using a pipe(|) to join two or more commands together.for example:
  grep "01254" order*|less
  this command searches through all files whose names begin with order to find lines contains the word 01254.


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