I made a program that extracts quotes while retaining special inner quotes (in this case an 'x' followed by an apostrophe). The original program is far more complicated than this, but I wanted to make it simple to troubleshoot.
I want to take these two perl commands and have the first command's results be piped into the second commands input but while only running perl once:
Input: ['Say, x'Hix'']
Output: Say, x'Hix'
Taking the output of the first command:
Result (proper): Say, 'Hi'
I realise that I could easily just run perl twice and pipe them into eachother, but running perl twice seems inefficient; especially given that this command is ran thousands of times:
I've tried combining both commands in the code below, but it doesn't seem to be taking the output of the first command as input for the second:
Result (not what I want):
What is the correct format for a single command that would combine portions of 2 different lines in the command history? I'm using a C shell. Here's a simplified command history to clarify:
4 rm file1
5 ls -ld file2 file3 file4
6 cat file 5
With the above history, what would be the... (5 Replies)
I would like to change the lines:
originalline1
originalline2
to:
originalline1new
originalline1newline
originalline2new
originalline2newline
To do this, id like to combine the commands:
sed 's/^/&new/g' file > newfile1
and
sed '/^/ a\\
newline\\
\\ (2 Replies)
Hello all,
I am trying to list and count all the files of a particular type in any given directory. I can use the commands separately but when I combine them they do not give an output.
The command for counting the files is ls -1 | wc -l and for listing all the file of particular type say... (2 Replies)
Is there anyway to achieve "find /home -name "*.bashrc" 2>/dev/null" and "PS1="\n>"" in the same command? I just wanna add a line to the previous command to change the PS1 variable to ">". (1 Reply)
Hi Guys,
I am looking to optimze these 5 SSH lines to a single SSH to get my machine to not hang! lol!
cat hosts.lst | xargs -n1 -t -i echo 'home/util/timeout 6 0 ssh -q {} top -b > util/{}.top &' >> r_query_info
cat hosts.lst | xargs -n1 -t -i echo 'home/util/timeout 6 0 ssh -q {} uname -r... (5 Replies)
hey can anyone tell me how can i combine these two commands so that it is executed only once, but gives me both the results.
IDLE=`sar 30 6 | grep Average | awk '{print $1 $5}' `
sar 30 120 | awk '{print $1" "$5}' >> mailx -m -s "$MSG" xyz@abc.com. (5 Replies)
Hi,
I have a directory with some XML files in it. I can use wildcards to get the list of XMLs I want
say I have following XMLs in same dir
Employee1.xml
Employee2.xml
Employee3.xml
and
Salary1.xml
Salary2.xml
Salary3.xml
apart from other .txt .dat files etc
I want to write a unix... (7 Replies)
I have a directory of 3000 files without extensions (Solaris 5.10).
I would like to iterate the file names through the 'file' command and output their mime types (most are pdf or jpg, but a very few might be psd or swf which show simply as 'data')
So, I would like the output of the 'ls'... (2 Replies)
Hello all,
I need to send an attachment and text in the body, both in the same Email.
Below are two cammand that send the required data in separate Emails. I need to combine them so that I get just 1 Email containing the attachment & text in the body.
uuencode ${filename} "${file_}" |... (6 Replies)
Discussion started by: Junaid Subhani
6 Replies
LEARN ABOUT OSX
shell
Shell(3pm) Perl Programmers Reference Guide Shell(3pm)NAME
Shell - run shell commands transparently within perl
SYNOPSIS
use Shell qw(cat ps cp);
$passwd = cat('</etc/passwd');
@pslines = ps('-ww'),
cp("/etc/passwd", "/tmp/passwd");
# object oriented
my $sh = Shell->new;
print $sh->ls('-l');
DESCRIPTION
Caveats
This package is included as a show case, illustrating a few Perl features. It shouldn't be used for production programs. Although it does
provide a simple interface for obtaining the standard output of arbitrary commands, there may be better ways of achieving what you need.
Running shell commands while obtaining standard output can be done with the "qx/STRING/" operator, or by calling "open" with a filename
expression that ends with "|", giving you the option to process one line at a time. If you don't need to process standard output at all,
you might use "system" (in preference of doing a print with the collected standard output).
Since Shell.pm and all of the aforementioned techniques use your system's shell to call some local command, none of them is portable across
different systems. Note, however, that there are several built in functions and library packages providing portable implementations of
functions operating on files, such as: "glob", "link" and "unlink", "mkdir" and "rmdir", "rename", "File::Compare", "File::Copy",
"File::Find" etc.
Using Shell.pm while importing "foo" creates a subroutine "foo" in the namespace of the importing package. Calling "foo" with arguments
"arg1", "arg2",... results in a shell command "foo arg1 arg2...", where the function name and the arguments are joined with a blank. (See
the subsection on Escaping magic characters.) Since the result is essentially a command line to be passed to the shell, your notion of
arguments to the Perl function is not necessarily identical to what the shell treats as a command line token, to be passed as an individual
argument to the program. Furthermore, note that this implies that "foo" is callable by file name only, which frequently depends on the
setting of the program's environment.
Creating a Shell object gives you the opportunity to call any command in the usual OO notation without requiring you to announce it in the
"use Shell" statement. Don't assume any additional semantics being associated with a Shell object: in no way is it similar to a shell
process with its environment or current working directory or any other setting.
Escaping Magic Characters
It is, in general, impossible to take care of quoting the shell's magic characters. For some obscure reason, however, Shell.pm quotes
apostrophes ("'") and backslashes ("") on UNIX, and spaces and quotes (""") on Windows.
Configuration
If you set $Shell::capture_stderr to 1, the module will attempt to capture the standard error output of the process as well. This is done
by adding "2>&1" to the command line, so don't try this on a system not supporting this redirection.
Setting $Shell::capture_stderr to -1 will send standard error to the bit bucket (i.e., the equivalent of adding "2>/dev/null" to the
command line). The same caveat regarding redirection applies.
If you set $Shell::raw to true no quoting whatsoever is done.
BUGS
Quoting should be off by default.
It isn't possible to call shell built in commands, but it can be done by using a workaround, e.g. shell( '-c', 'set' ).
Capturing standard error does not work on some systems (e.g. VMS).
AUTHOR
Date: Thu, 22 Sep 94 16:18:16 -0700
Message-Id: <9409222318.AA17072@scalpel.netlabs.com>
To: perl5-porters@isu.edu
From: Larry Wall <lwall@scalpel.netlabs.com>
Subject: a new module I just wrote
Here's one that'll whack your mind a little out.
#!/usr/bin/perl
use Shell;
$foo = echo("howdy", "<funny>", "world");
print $foo;
$passwd = cat("</etc/passwd");
print $passwd;
sub ps;
print ps -ww;
cp("/etc/passwd", "/etc/passwd.orig");
That's maybe too gonzo. It actually exports an AUTOLOAD to the current package (and uncovered a bug in Beta 3, by the way). Maybe the
usual usage should be
use Shell qw(echo cat ps cp);
Larry Wall
Changes by Jenda@Krynicky.cz and Dave Cottle <d.cottle@csc.canterbury.ac.nz>.
Changes for OO syntax and bug fixes by Casey West <casey@geeknest.com>.
$Shell::raw and pod rewrite by Wolfgang Laun.
Rewritten to use closures rather than "eval "string"" by Adriano Ferreira.
perl v5.12.5 2012-11-03 Shell(3pm)