unix commands

Yifat has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: unix commands by lhoward (Vicar) on Jun 04, 2001 at 18:04 UTC
Try IPC::Open3, it lets you open a process for writing, and reading from stdout and stderr. `$pid = open3(\WTRFH, \RDRFH, \*ERRFH, 'some cmd and args', 'optarg', ...);` [download]	[reply] [d/l]
Re: unix commands by VSarkiss (Monsignor) on Jun 04, 2001 at 18:50 UTC
Careful: the shell syntax you've written: `>& filename` is for C shell and its ilk. Generally, perl will use a Bourne-type shell for implementing `system()`. Basically, the `>& file` syntax in C shells is equivalent to the Bourne shell `>file 2>&1` syntax others have posted here. If you're at the stage where you need finer-grain control over redirection, error output, etc., than the simple facilities of `system`, consider making more use of Perl's own built-ins. You can search the CPAN for process management tools, (which are usually platform-specific, such as `Win32::Process` or `OS2::Process`), or just write your own fork/exec.	[reply] [d/l] [select]
Re: unix commands by converter (Priest) on Jun 04, 2001 at 18:08 UTC
If you want to direct the output of both `stdout` and `stderr` to the same file, use: `system "command > output.txt 2>&1";` [download] "`2>&1`" basically means "redirect filehandle 2 (stderr) to the same place as filehandle 1 (stdout)".	[reply] [d/l]
Re: unix commands by BigJoe (Curate) on Jun 04, 2001 at 17:58 UTC
I am not sure using the system command but when I use backticks I use 2>filename to do this. my $testpage = `/var/www/html/wvWare --config=/var/www/html/wvHtml.xml + 2>/dev/null /tmp/abc.tmp`; [download] (I use this to convert word docs to HTML on my Linux box.) 2> takes care of the errors. Maybe it will work on the system() command. --BigJoe Learn patience, you must. Young PerlMonk, craves Not these things. Use the source Luke.	[reply] [d/l]
Re: unix commands by virtualsue (Vicar) on Jun 04, 2001 at 19:32 UTC
Hi Yifat, >& is not valid bourne shell syntax (looks like csh to me), and /bin/sh -c (bourne shell) is what Perl uses in order to execute the `system` command string on unix systems. See this for the full scoop on `system`. In /bin/sh redirection works like so: `ls > ls.out -- Send stdout of ls to ls.out mycmd > mycmd.out 2> mycmd.err -- Send stdout to mycmd.out, stderr to +mycmd.err If you'd like stdout and stderr to go to the same location, use mycmd > mycmd.log 2>&1` [download] It can get a lot fancier than that, see your local system documentation (man sh) or look here http://www.torget.se/users/d/Devlin/shell/man_sh.html.	[reply] [d/l] [select]
Re: unix commands by Cirollo (Friar) on Jun 04, 2001 at 18:57 UTC
I think your problem might be caused by shell semantics; command >& file works in most cases but is not preferred. Try using &> instead, which according to the bash manpage is semantically equivalent to >word 2>&1 Update: I shouldn't go off and do work in the middle of writing a reply, or two other people will beat me to it ;)	[reply]