問題描述
找不到傳遞給使用 Perl“系統”命令調用的程序的參數 (Cannot find argument passed to program called using Perl "system" command)
I'm writing a Perl script to run an external program on every file in a directory. This program converts files from one format to another. Here's the deal...
When I run the program from the command line, everything works as it should:
computer.name % /path/program /inpath/input.in /outpath/output.out
converting: /inpath/input.in to /outpath/output.out
computer.name %
Here's the code I wrote to convert all files in a directory (listed in "file_list.txt"):
#!/usr/bin/perl ‑w
use warnings;
use diagnostics;
use FileHandle;
use File::Copy;
# Set simulation parameters and directories
@test_dates = ("20110414");
$listfile = "file_list.txt";
$execname = "/path/program";
foreach $date (@test_dates)
{
# Set/make directories
$obs_file_dir = "inpath";
$pred_file_dir = "outpath";
mkdir "$pred_file_dir", 0755 unless ‑d "$pred_file_dir";
# Read input file names to array
$obs_file_list = $obs_file_dir . $listfile;
open(DIR, $obs_file_list) or die "Could not open file!";
@obs_files = <DIR>;
close(DIR);
# Convert and save files
foreach $file (@obs_files)
{
$file =~ s/(\*)//g;
$infile = $obs_file_dir . $file;
$outfile = $pred_file_dir . $file;
$outfile =~ s/in/out/g;
print $infile . "\n";
@arg_list = ($execname, $infile, $outfile);
system(@arg_list);
}
}
The output shows me the following error for every file in the list:
computer.name % perl_script_name.pl
/inpath/input.in
converting: /inpath/input.in to /outpath/output.out
unable to find /inpath/input.in
stat status=‑1
error while processing the product
I verified every file is in the proper place and have no idea why I am getting this error. Why can't the files be found? When I manually pass the arguments using the command line, no problem. When I pass the arguments through a variable via a system call, they can't be found even though the path and file names are correct.
Your advice is greatly appreciated!
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參考解法
方法 1:
Your list of files (@obs_files) comes from reading in a file via @obs_files = <DIR>;
When you do that, each element of array will be a line from a file (e.g. directory listing), with the line being terminated by a newline character.
Before using it, you need to remove the newline character via chomp($file).
Please note that s/(\*)//g; does NOT remove that trailing newline!