Howto redirect the standard input and output of a command shell script:
STDERR and STDOUT together:
To capture a command’s STDOUT but discard its STDERR:
$output = `cmd 2>/dev/null`;
To capture a command’s STDERR but discard its STDOUT (ordering is important here):
$output = `cmd 2>&1 1>/dev/null`;
To exchange a command’s STDOUT and STDERR in order to capture the STDERR but leave its STDOUT to come out the old STDERR:
$output = `cmd 3>&1 1>&2 2>&3 3>&-`;
To read both a command’s STDOUT and its STDERR separately, it’s easiest to redirect them separately to files, and then read from those files when the program is done:
system("program args 1>program.stdout 2>program.stderr");
If you want to test whether you can write to a file or if a direcory exists,
this may help a little when writing clean scripts with appropriate error messages
So here is a little collection of the most common file test operators in Perl:
File Test Operators
Test Meaning
-r File or directory is readable by this (effective) user or group
-w File or directory is writable by this (effective) user or group
-x File or directory is executable by this (effective) user or group
-o File or directory is owned by this (effective) user
-R File or directory is readable by this real user or group
-W File or directory is writable by this real user or group
-X File or directory is executable by this real user or group
-O File or directory is owned by this real user
-e File or directory name exists
-z File exists and has zero size (always false for directories)
-s File or directory exists and has nonzero size (the value is the size in bytes)
-f Entry is a plain file
-d Entry is a directory
-l Entry is a symbolic link
-S Entry is a socket
Test Meaning
-p Entry is a named pipe (a “fifo”)
-b Entry is a block-special file (like a mountable disk)
-c Entry is a character-special file (like an I/O device)
-u File or directory is setuid
-g File or directory is setgid
-k File or directory has the sticky bit set
-t The filehandle is a TTY (as reported by theisatty()system function; filenames can’t be tested by this test)
-T File looks like a “text” file
-B File looks like a “binary” file
-M Modification age (measured in days)
-A Access age (measured in days)
Languages: Chinese-simp, Chinese-trad, Dutch, English, French, German, Greek, Italian, Japanese, Korean, Portuguese, Russian, Spanish
Requirements:
IO::String
WWW::Babelfish
#!/usr/bin/perl
use strict;
use warnings;
use WWW::Babelfish;
# text to translate
my $text_source = 'I like to test this service.';
# create the Babelfish service
my $service = WWW::Babelfish->new(
service => 'Babelfish',
);
# check for errors
if (not defined $service) {
die "Babelfish server unavailable";
}
# show text to be translated
print "[EN] $text_source\n";
# translate to Italian
my $text_target = $service->translate(
source => 'English', # source language
destination => 'Italian', # destination language
text => $text_source, # text to translate
);
if (not defined $text_target) {
print "Error while translating to Italian";
}
else {
print "[FR] $text_target\n";
}
