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Full Discussion: help running strace
Top Forums UNIX for Advanced & Expert Users help running strace Post 302089986 by klam on Thursday 21st of September 2006 08:03:59 PM
Old 09-21-2006
help running strace

OK so I wanted to know how does grep outputs to the pipe and how sort reads from it. So I run a strace over "grep blah myfile | sort" and this is what I got:

open("myfile", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0600, st_size=84, ...}) = 0
read(3, "blah blah and blah cause of blah"..., 32768) = 84
fstat64(1, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7fe8000
read(3, "", 32768) = 0
close(3) = 0
write(1, "blah blah and blah cause of blah"..., 85) = 85
close(1) = 0
munmap(0xb7fe8000, 4096) = 0
exit_group(0) = ?
Process 14533 detached
blah blah and blah cause of blah
find blah myfile blah grep it.
this is my blah file

I know that grep nor sort are aware of the pipe, they just input/output to the stdin/stdout... the pipe just connect them, that's how pipes works as far as I know... but what I don't see in this code is how grep is outputing to the pipe (stdout) and how is sort reading from the pipe (stdin). Is there anyway to check that relation? All I can tell from the code I bolded is:

MyFile -> Grep --------------------------> stdout

Unless "read(3, "", 32768)" has anything to do with the sort process.
Thanks in advance.
 

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SQL::Translator::Schema::Procedure(3pm) 		User Contributed Perl Documentation		   SQL::Translator::Schema::Procedure(3pm)

NAME
SQL::Translator::Schema::Procedure - SQL::Translator procedure object SYNOPSIS
use SQL::Translator::Schema::Procedure; my $procedure = SQL::Translator::Schema::Procedure->new( name => 'foo', sql => 'CREATE PROC foo AS SELECT * FROM bar', parameters => 'foo,bar', owner => 'nomar', comments => 'blah blah blah', schema => $schema, ); DESCRIPTION
"SQL::Translator::Schema::Procedure" is a class for dealing with stored procedures (and possibly other pieces of nameable SQL code?). METHODS
new Object constructor. my $schema = SQL::Translator::Schema::Procedure->new; parameters Gets and set the parameters of the stored procedure. $procedure->parameters('id'); $procedure->parameters('id', 'name'); $procedure->parameters( 'id, name' ); $procedure->parameters( [ 'id', 'name' ] ); $procedure->parameters( qw[ id name ] ); my @parameters = $procedure->parameters; name Get or set the procedure's name. $procedure->name('foo'); my $name = $procedure->name; sql Get or set the procedure's SQL. $procedure->sql('select * from foo'); my $sql = $procedure->sql; order Get or set the order of the procedure. $procedure->order( 3 ); my $order = $procedure->order; owner Get or set the owner of the procedure. $procedure->owner('nomar'); my $sql = $procedure->owner; comments Get or set the comments on a procedure. $procedure->comments('foo'); $procedure->comments('bar'); print join( ', ', $procedure->comments ); # prints "foo, bar" schema Get or set the procedures's schema object. $procedure->schema( $schema ); my $schema = $procedure->schema; equals Determines if this procedure is the same as another my $isIdentical = $procedure1->equals( $procedure2 ); AUTHORS
Ken Youens-Clark <kclark@cshl.org>, Paul Harrington <Paul-Harrington@deshaw.com>. perl v5.14.2 2012-01-18 SQL::Translator::Schema::Procedure(3pm)
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