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Full Discussion: awk, sed and a shell doubts
Top Forums Shell Programming and Scripting awk, sed and a shell doubts Post 302229795 by royalibrahim on Thursday 28th of August 2008 03:22:27 AM
Old 08-28-2008
Quote:
Originally Posted by gnsxhj
Code:
sed ':a;$!{N;s/\n//;ba;}'

maybe i can explain some details of this script:
:a : the label of the branch (u will see ba in the end of script), u can use any alphabet as u wish, so that's a loop of sed
$!: except the last line will do the following actions :
N: read the next line into the pattern space, so, there are two lines in the pattern space
s/\n/ /: replace the \n with the " ", so that will combine the two lines to one
ba: return to the top of the script until the all lines have been read, print it!

i hope that will helpful :-)
Great explanations. Thanks to era, sudhamacs, gnsxhj

Now, I can explain this script's logic by my own:

Code:
sed ':a;$!{N;ba;}; $s/\n/ /g'

:a -- label of the branch that acts as a loop of sed until ba, any alphabet can be used
$! -- except the last line do the following actions:
N -- read next line into the pattern space (adding up multiple lines separated by '\n')
ba -- return to the top of the script until all the lines are read and then print it
s/\n/ /g -- replace '\n' with "<space>" globally in the pattern space, that combines all the lines in to one
 

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LEARN ABOUT DEBIAN

pyp

PYP(1)							      General Commands Manual							    PYP(1)

NAME

       pyp - The Pyed Piper: A Modern Python Alternative to awk, sed and Other Unix Text Manipulation Utilities

SYNOPSIS

       pyp [options] files ...

DESCRIPTION

       pyp,  the  Pyed Piper, is a command line tool for text manipulation. It is similar to awk and sed in functionality, but its subcommands are
       Python based, and thus more familiar to many programmers.

       It can operate both on a per-line base and on the complete input stream.  Different features can be pipelined in a single command by  using
       the pipe character familiar from shell commands.

       pyp  backs  up  its  input  for reruns with modified commands, and can save commands as macros. On the downside, the rerun feature makes it
       unsuitable for continuous pipe operation.

OPTIONS

       These programs follow the usual GNU command line syntax, with long options starting with  two  dashes  (`-').   A  summary  of  options	is
       included below.	For a complete description, use --manual.

       -h, --help
	      Show this help message and exit.

       -m, --manual
	      Prints out extended help.

       -l, --macro_list
	      Lists all available macros.

       -s MACRO_SAVE_NAME, --macro_save=MACRO_SAVE_NAME
	      Saves current command as macro. use "#" for adding
	      comments	EXAMPLE:
	      pyp -s "great_macro # prints first letter" "p[1]".

       -f MACRO_FIND_NAME, --macro_find=MACRO_FIND_NAME
	      Searches for macros with keyword or user name.

       -d MACRO_DELETE_NAME, --macro_delete=MACRO_DELETE_NAME
	      Deletes specified public macro.

       -g, --macro_group
	      Specify group macros for save and delete; default is user.

       -t TEXT_FILE, --text_file=TEXT_FILE
	      Specify text file to load. For advanced users,
	      you should typically cat a file into pyp.

       -x, --execute
	      Execute all commands.

       -c, --turn_off_color
	      Prints raw, uncolored output.

       -u, --unmodified_config
	      Prints out generic PypCustom.py config file.

       -b BLANK_INPUTS, --blank_inputs=BLANK_INPUTS
	      Generate this number of blank input lines; useful for
	      generating numbered lists with variable 'n'.

       -n, --no_input
	      Use with command that generates output with no input;
	      same as --dummy_input 1.

       -k, --keep_false
	      Print blank lines for lines that test as False.
	      default is to filter out False lines from the output.

       -r, --rerun
	      Rerun based on automatically cached data from the last run.
	      Use this after executing "pyp", pasting input into the shell,
	      and hitting CTRL-D.

SEE ALSO

       awk(1), grep(1), sed(1).

AUTHOR

       pyp was written by Toby Rosen <tobyrosen@gmail.com>.

       This manual page was written by Khalid El Fathi <khalid@elfathi.fr>, for the Debian project (and may be used by others).

								  March 19, 2012							    PYP(1)
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