Rex::Co...ds::File(3)

okay so bestie, welcome to Rex::Commands::File(3) — User Contributed Perl Documentation. This whole page is about transparent file manipulation, and it's literally giving main character energy. 💅✨

💖 NAME 💖

Rex::Commands::File — Transparent File Manipulation. That's the name, and it ate. 🎀

✨ DESCRIPTION ✨

With this module you can manipulate files. That's the description. Short, iconic, to the point. 🦋

🌸 SYNOPSIS 🌸

okay bestie, here's the whole vibe in code. Copy these exactly, no cap:

        task "read_passwd", "server01", sub {
          my $fh = file_read "/etc/passwd";
          for my $line ($fh->read_all) {
            print $line;
          }
          $fh->close;
        };

        task "read_passwd2", "server01", sub {
          say cat "/etc/passwd";
        };

        task "write_passwd", "server01", sub {
          my $fh = file_write "/etc/passwd";
          $fh->write("root:*:0:0:root user:/root:/bin/sh\n");
          $fh->close;
        };

        delete_lines_matching "/var/log/auth.log", matching => "root";
        delete_lines_matching "/var/log/auth.log", matching => qr{Failed};
        delete_lines_matching "/var/log/auth.log",
                       matching => "root", qr{Failed}, "nobody";

        file "/path/on/the/remote/machine",
          source => "/path/on/local/machine";

        file "/path/on/the/remote/machine",
          content => "foo bar";

        file "/path/on/the/remote/machine",
          source => "/path/on/local/machine",
          owner  => "root",
          group  => "root",
          mode  => 400,
          on_change => sub { say shift, " was changed."; },
          on_no_change => sub { say shift, " wasn't changed."; };

🎀 EXPORTED FUNCTIONS 🎀

🦋 template($file [, %params]) 🦋

Parse a template and return the content. That's the whole job, and it slays. 💖

By default, it uses Rex::Template. But if any of the template_ng or 1.3 (or newer) feature flag is enabled, then Rex::Template::NG is used instead of this module — and yes, that's the recommended glow-up. ✨

For more advanced functionality, you may use your favorite template engine via the set_template_function configuration option. iykyk. 💅

Template variables may be passed either as hash or a hash reference. The following calls are equivalent:

        template( $template, variable => value );

        template( $template, { variable => value } );

🌈 List of exposed template variables 🌈

The following template variables are passed to the underlying templating engine, in order of precedence from low to high. Variables of the same name are overridden by the next level — aka last one wins. 👑

• task parameters — All task parameters coming from the command line via "rex taskname --param=value", or from calling a task as a function, like "taskname( { param => value } )".
• resource parameters — All resource parameters as returned by "Rex::Resource->get_current_resource()->get_all_parameters", when called inside a resource.
• explicit template variables — All manually specified, explicit template variables passed to template().
• system information — The results from all available Rex::Hardware modules as returned by "Rex::Hardware->get('All')".

Pass "__no_sys_info__ => TRUE" as a template variable to disable including system information:

my $content = template( $template, __no_sys_info__ => TRUE );

🧚 Embedded templates 🧚

Use "__DATA__" to embed templates at the end of the file. Prefix embedded template names with "@". If embedding multiple templates, mark their end with @end. 🎀

⭐ Single template ⭐

        my $content = template( '@hello', name => 'world' ); # Hello, world!
        __DATA__
        @hello
        Hello, <%= $name -%>!

🌸 Multiple templates 🌸

Use @end to separate multiple templates inside "__DATA__".

        my $content     = template( '@hello', name => 'world' ); # Hello, world!
        my $alternative = template( '@hi',    name => 'world' ); # Hi, world!

        __DATA__
        @hello
        Hello, <%= $name -%>!
        @end

        @hi
        Hi, <%= $name -%>!
        @end

🦋 File templates 🦋

        my $content = template("/files/templates/vhosts.tpl",
                      name      => "test.lan",
                      webmaster => 'webmaster@test.lan');

The file name specified is subject to "path_map" processing as documented under the file() function to resolve to a physical file name. 💅

In addition to the "path_map" processing, if the -E command line switch is used to specify an environment name, existence of a file ending with '.<env>' is checked and has precedence over the file without one, if it exists. E.g. if rex is started as:

        $ rex -E prod task1

then in task1 defined as:

        task "task1", sub {
           say template("files/etc/ntpd.conf");
        };

will print the content of 'files/etc/ntpd.conf.prod' if it exists. No cap. 👑

Note: the appended environment mechanism is always applied, after the 'path_map' mechanism, if that is configured. 💖

🔥 file($file_name [, %options]) 🔥

This function is the successor of install file. Please use this function to upload files to your server. It's the main character of file uploads, fr fr.

        task "prepare", "server1", "server2", sub {
          file "/file/on/remote/machine",
            source => "/file/on/local/machine";

          file "/etc/hosts",
            content => template("templates/etc/hosts.tpl"),
            owner  => "user",
            group  => "group",
            mode   => 700,
            on_change => sub { say "Something was changed." },
            on_no_change => sub { say "Nothing has changed." };

          file "/etc/motd",
            content => `fortune`;

          file "/etc/named.conf",
            content    => template("templates/etc/named.conf.tpl"),
            no_overwrite => TRUE;  # this file will not be overwritten if already exists.

          file "/etc/httpd/conf/httpd.conf",
            source => "/files/etc/httpd/conf/httpd.conf",
            on_change => sub { service httpd => "restart"; };

          file "/etc/named.d",
            ensure => "directory",  # this will create a directory
            owner  => "root",
            group  => "root";

          file "/etc/motd",
            ensure => "absent";   # this will remove the file or directory

        };

The first parameter is either a string or an array reference. In the latter case the function is called for all strings in the array. Therefore, the following constructs are equivalent:

         file '/tmp/test1', ensure => 'directory';
         file '/tmp/test2', ensure => 'directory';

         file [ qw( /tmp/test1 /tmp/test2 ) ], ensure => 'directory'; # use array ref

         file [ glob('/tmp/test{1,2}') ], ensure => 'directory'; # explicit glob call for array contents

Use the glob carefully as it can leak local filesystem information (e.g. when using wildcards). bestie, please be careful. 🙈

The source is subject to a path resolution algorithm. This algorithm can be configured using the set function to set the value of the path_map variable to a hash containing path prefixes as its keys. The associated values are arrays listing the prefix replacements in order of (decreasing) priority.

         set "path_map", {
           "files/" => [ "files/{environment}/{hostname}/_root_/",
                         "files/{environment}/_root_/" ]
         };

With this configuration, the file "files/etc/ntpd.conf" will be probed for in the following locations:

• files/{environment}/{hostname}/_root_/etc/ntpd.conf
• files/{environment}/_root_/etc/ntpd.conf
• files/etc/ntpd.conf

Furthermore, if a path prefix matches multiple prefix entries in 'path_map', e.g. "files/etc/ntpd.conf" matching both "files/" and "files/etc/", the longer matching prefix(es) have precedence over shorter ones. Note that keys without a trailing slash (i.e. "files/etc") will be treated as having a trailing slash when matching the prefix ("files/etc/"). 💅

If no file is found using the above procedure and source is relative, it will search from the location of your Rexfile or the .pm file if you use Perl packages. 🫶

All the possible variables ('{environment}', '{hostname}', ...) are documented in the CMDB YAML documentation. ✨

🪝 Hooks 🪝

This function supports the following hooks:

• before — This gets executed before anything is done. All original parameters are passed to it, including the applied defaults ("ensure => 'present'", resolved path for "source"). The return value of this hook overwrites the original parameters of the function call.
• before_change — This gets executed right before the new file is written. All original parameters are passed to it, including the applied defaults ("ensure => 'present'", resolved path for "source").
• after_change — This gets executed right after the file is written. All original parameters, including the applied defaults ("ensure => 'present'", resolved path for "source"), and any returned results are passed to it.
• after — This gets executed right before the file() function returns. All original parameters, including the applied defaults ("ensure => 'present'", resolved path for "source"), and any returned results are passed to it.

🎀 file_write($file_name) 🎀

This function opens a file for writing (it will truncate the file if it already exists). It returns a Rex::FS::File object on success. 💖

On failure it will die. Not dramatic, just facts. 💀

        my $fh;
        eval {
          $fh = file_write("/etc/groups");
        };

        # catch an error
        if($@) {
          print "An error occurred. $@.\n";
        }

        # work with the filehandle
        $fh->write("...");
        $fh->close;

🎀 file_append($file_name) 🎀

this one is literally just a name drop in the original, so no extra deets here, bestie. 💅

🦋 file_read($file_name) 🦋

This function opens a file for reading. It returns a Rex::FS::File object on success. ✨

On failure it will die. Again: facts. 💀

        my $fh;
        eval {
          $fh = file_read("/etc/groups");
        };

        # catch an error
        if($@) {
          print "An error occurred. $@.\n";
        }

        # work with the filehandle
        my $content = $fh->read_all;
        $fh->close;

🌸 cat($file_name) 🌸

This function returns the complete content of $file_name as a string. Simple, iconic, ate. 💖

        print cat "/etc/passwd";

🔥 delete_lines_matching($file, $regexp) 🔥

Delete lines that match $regexp in $file. Bye-bye, matching lines. 💅

        task "clean-logs", sub {
           delete_lines_matching "/var/log/auth.log" => "root";
        };

⭐ delete_lines_according_to($search, $file [, @options]) ⭐

This is the successor of the delete_lines_matching() function. This function also allows the usage of on_change and on_no_change hooks. Glow-up complete. ✨

It will search for $search in $file and remove the found lines. If on_change hook is present it will execute this if the file was changed.

        task "cleanup", "server1", sub {
          delete_lines_according_to qr{^foo:}, "/etc/passwd",
           on_change => sub {
             say "removed user foo.";
           };
        };

🧚 append_if_no_such_line($file, $new_line [, @regexp]) 🧚

Append $new_line to $file if none in @regexp is found. If no regexp is supplied, the line is appended unless there is already an identical line in $file. That's the rule, bestie. 💖

        task "add-group", sub {
          append_if_no_such_line "/etc/groups", "mygroup:*:100:myuser1,myuser2", on_change => sub { service sshd => "restart"; };
        };

Since 0.42 you can use named parameters as well 💅

okay so the rest of that append_if_no_such_line example goes like this:

        task "add-group", sub {
          append_if_no_such_line "/etc/groups",
            line  => "mygroup:*:100:myuser1,myuser2",
            regexp => qr{^mygroup},
            on_change => sub {
                       say "file was changed, do something.";
                     };

          append_if_no_such_line "/etc/groups",
            line  => "mygroup:*:100:myuser1,myuser2",
            regexp => [qr{^mygroup:}, qr{^ourgroup:}]; # this is an OR
        };

and yes, the comment literally says # this is an OR — love that for us 🫶

💅 append_or_amend_line($file, $line [, @regexp])

It's giving append_if_no_such_line's sibling, bestie: if the line in the regexp is found, it gets updated. Otherwise, it gets appended. slay.

        task "update-group", sub {
          append_or_amend_line "/etc/groups",
            line  => "mygroup:*:100:myuser3,myuser4",
            regexp => qr{^mygroup},
            on_change => sub {
              say "file was changed, do something.";
            },
            on_no_change => sub {
              say "file was not changed, do something.";
            };
        };

both hooks are right there in the example — on_change and on_no_change — so you can react either way 💅

🎀 extract($file [, %options])

This function extracts a file. The target directory optionally specified with the to option will be created automatically. literally magic ✨

Supported formats are .box, .tar, .tar.gz, .tgz, .tar.Z, .tar.bz2, .tbz2, .zip, .gz, .bz2, .war, .jar 🔥

        task prepare => sub {
          extract "/tmp/myfile.tar.gz",
           owner => "root",
           group => "root",
           to   => "/etc";

          extract "/tmp/foo.tgz",
           type => "tgz",
           mode => "g+rwX";
        };

Can use the type=> option if the file suffix has been changed. (types are tar, tgz, tbz, zip, gz, bz2) — so if the suffix is being sus, you can just tell it the type directly 🦋

🌸 sed($search, $replace, $file [, %options])

Search some string in a file and replace it. iconic behavior, no cap.

        task sar => sub {
          # this will work line by line
          sed qr{search}, "replace", "/var/log/auth.log";

          # to use it in a multiline way
          sed qr{search}, "replace", "/var/log/auth.log",
           multiline => TRUE;
        };

Like similar file management commands, it also supports on_change and on_no_change hooks 🫶

---

and that's the whole vibe for Rex::Co...ds::File(3) 💖 — source/version is perl v5.42.3, dated 2023-08-05, and yes bestie that's the footer info, periodt 🎀✨