Shell command combination with the free Swiss File Knife allows to write easy but powerful single-line scripts, for instant file and text processing.

sfk command chaining reference:

several commands can be combined in a so-called "command chain".
this is done by appending command names prefixed by "+", for example:

sfk list docs .txt +ffilter -+foo
   "list" produces a filename list and passes this to "filefilter".
   ffilter reads the contents of these files looking for word "foo".

chain data types
   three types of data can be passed from one command to another:

      - filename lists.
      - plain text records (lines).
      - stream text or binary data.

   output is dependent on command. for example, sfk select produces
   filename lists, sfk filter makes plain text records, xex/xed can
   produce streams of text or binary data.

chain data type conversion
   vice versa, some commands accept filenames, or text input, or both.
   depending on what you want to do you may have to convert between
   this types of data. this can be done by the keywords:

      +texttofilenames or +ttf
      +filenamestotext or +ftt

   however, most sfk commands try to do such conversions automatically.

using chain data between commands
   sfk cmd1 ... +then cmd2   does not pass any data to cmd2,
                             prints cmd1 output to terminal.
   sfk ... +toterm           dumps current chain content to terminal.
   sfk ... +tofile outfile   dumps chain content to file outfile.
   sfk ... +tovoid +cmd2     does not pass any data to cmd2,
                             drops cmd1 chain text silently.
   in all cases, the chain is cleared. if another command is following,
   it will receive no input from the chain.

no data tunneling
   chain data can only be passed
   - from a data producing command like  +echo mytext
   - directly to the following command
     if it consumes data like            +setvar myvar
   - but not through a non consumer like +tell othertext
   bad example:
     sfk echo mytext +tell hello +setvar a
       stops with an error at setvar: no chain data
   good example:
     sfk echo mytext +setvar a +tell hello +getvar
       mytext is stored, hello is printed

   in other words, in a command chain like:
   sfk cmd1 +cmd2 +cmd3 +cmd4 +cmd5
   it is not possible to send data from cmd1 to cmd3/4/5
   if cmd2 does not use any chain data (e.g. if, tell).
   since sfk 1.9.3 this bypassing of cmd2 is disabled
   to avoid conflicts by unwanted chain data in cmd3/4/5.
   the only exception is: cmd1 +label name +cmd2
   use global option -keepdata or set environment variable
      set SFK_CONFIG=keepdata
   for the sfk 1.9.2 behaviour which was inconsistent
   and worked only with some commands.

using chain data with call / label / end
   sfk ... +call myfunc      passes no chain data into myfunc
   sfk label ... +end        returns no chain data

if chaining stops with "no files, stopping at x":

   this means command x expects a list of filenames,
   but the previous command did not produce any.
   you have three options then:

   - use +then x if command x should never receive any
     filenames from a previous command.

   - or add -keepchain at the preceeding command, or
     directly after sfk, to enforce execution of command x.

   - or use -nonote to suppress the "no files" message.

   note that -keepchain is default since sfk 1.9.9.
   if you get a 'no files' stop although, look in options
   and SFK_CONFIG if 'stoponempty' is set.

scope and lifetime of options
   most options are valid only for the command where they are specified.
   if another command follows in the chain, the option is reset.
   but some options may also be specified on a global scope.
   read more on that under "sfk help options".

global options
   -tracechain   get verbose output while sfk steps
                 through a command chain

more in the SFK Book
   the SFK Book contains long examples with input,
   output, script and detailed command explanations.
   type "sfk book" for more.

see also
   sfk batch     create an example script
   sfk help var  how to use sfk variables
   sfk script    about sfk scripting
   sfk call      calling a function in a script
   sfk label     possible options with label
   sfk if        conditional execution
   sfk goto      jump to a local label
   sfk for       repeat commands n times
   sfk load      load text or data for chaining
see also
   sfk script  - place sfk commands into a multi-line script file
   sfk samp    - examples for batch embedded sfk scripts