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File::Slurp(3pm)               User Contributed Perl Documentation               File::Slurp(3pm)

NAME
       File::Slurp - Simple and Efficient Reading/Writing/Modifying of Complete Files

SYNOPSIS
         use File::Slurp;

         # read in a whole file into a scalar
         my $text = read_file('/path/file');

         # read in a whole file into an array of lines
         my @lines = read_file('/path/file');

         # write out a whole file from a scalar
         write_file('/path/file', $text);

         # write out a whole file from an array of lines
         write_file('/path/file', @lines);

         # Here is a simple and fast way to load and save a simple config file
         # made of key=value lines.
         my %conf = read_file('/path/file') =~ /^(\w+)=(.*)$/mg;
         write_file('/path/file', {atomic => 1}, map "$_=$conf{$_}\n", keys %conf);

         # insert text at the beginning of a file
         prepend_file('/path/file', $text);

         # in-place edit to replace all 'foo' with 'bar' in file
         edit_file { s/foo/bar/g } '/path/file';

         # in-place edit to delete all lines with 'foo' from file
         edit_file_lines sub { $_ = '' if /foo/ }, '/path/file';

         # read in a whole directory of file names (skipping . and ..)
         my @files = read_dir('/path/to/dir');

DESCRIPTION
       This module provides subs that allow you to read or write entire files with one simple
       call. They are designed to be simple to use, have flexible ways to pass in or get the file
       contents and to be very efficient. There is also a sub to read in all the files in a
       directory.

   WARNING - PENDING DOOM
       Although you technically can, do NOT use this module to work on file handles, pipes,
       sockets, standard IO, or the "DATA" handle. These are features implemented long ago that
       just really shouldn't be abused here.

       Be warned: this activity will lead to inaccurate encoding/decoding of data.

       All further mentions of actions on the above have been removed from this documentation and
       that feature set will likely be deprecated in the future.

       In other words, if you don't have a filename to pass, consider using the standard "do {
       local $/; <$fh> }", or Data::Section/Data::Section::Simple for working with "__DATA__".

FUNCTIONS
       File::Slurp implements the following functions.

   append_file
               use File::Slurp qw(append_file write_file);
               my $res = append_file('/path/file', "Some text");
               # same as
               my $res = write_file('/path/file', {append => 1}, "Some text");

       The "append_file" function is simply a synonym for the "write_file" in File::Slurp
       function, but ensures that the "append" option is set.

   edit_file
               use File::Slurp qw(edit_file);
               # perl -0777 -pi -e 's/foo/bar/g' /path/file
               edit_file { s/foo/bar/g } '/path/file';
               edit_file sub { s/foo/bar/g }, '/path/file';
               sub replace_foo { s/foo/bar/g }
               edit_file \&replace_foo, '/path/file';

       The "edit_file" function reads in a file into $_, executes a code block that should modify
       $_, and then writes $_ back to the file. The "edit_file" function reads in the entire file
       and calls the code block one time. It is equivalent to the "-pi" command line options of
       Perl but you can call it from inside your program and not have to fork out a process.

       The first argument to "edit_file" is a code block or a code reference. The code block is
       not followed by a comma (as with "grep" and "map") but a code reference is followed by a
       comma.

       The next argument is the filename.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The options are passed through to the "write_file" in File::Slurp function. All options
       are described there.  Only the "binmode" and "err_mode" options are supported. The call to
       "write_file" in File::Slurp has the "atomic" option set so you will always have a
       consistent file.

   edit_file_lines
               use File::Slurp qw(edit_file_lines);
               # perl -pi -e '$_ = "" if /foo/' /path/file
               edit_file_lines { $_ = '' if /foo/ } '/path/file';
               edit_file_lines sub { $_ = '' if /foo/ }, '/path/file';
               sub delete_foo { $_ = '' if /foo/ }
               edit_file \&delete_foo, '/path/file';

       The "edit_file_lines" function reads each line of a file into $_, and executes a code
       block that should modify $_. It will then write $_ back to the file. It is equivalent to
       the "-pi" command line options of Perl but you can call it from inside your program and
       not have to fork out a process.

       The first argument to "edit_file_lines" is a code block or a code reference.  The code
       block is not followed by a comma (as with "grep" and "map") but a code reference is
       followed by a comma.

       The next argument is the filename.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The options are passed through to the "write_file" in File::Slurp function. All options
       are described there.  Only the "binmode" and "err_mode" options are supported. The call to
       "write_file" in File::Slurp has the "atomic" option set so you will always have a
       consistent file.

   ef
               use File::Slurp qw(ef);
               # perl -0777 -pi -e 's/foo/bar/g' /path/file
               ef { s/foo/bar/g } '/path/file';
               ef sub { s/foo/bar/g }, '/path/file';
               sub replace_foo { s/foo/bar/g }
               ef \&replace_foo, '/path/file';

       The "ef" function is simply a synonym for the "edit_file" in File::Slurp function.

   efl
               use File::Slurp qw(efl);
               # perl -pi -e '$_ = "" if /foo/' /path/file
               efl { $_ = '' if /foo/ } '/path/file';
               efl sub { $_ = '' if /foo/ }, '/path/file';
               sub delete_foo { $_ = '' if /foo/ }
               efl \&delete_foo, '/path/file';

       The "efl" function is simply a synonym for the "edit_file_lines" in File::Slurp function.

   overwrite_file
               use File::Slurp qw(overwrite_file);
               my $res = overwrite_file('/path/file', "Some text");

       The "overwrite_file" function is simply a synonym for the "write_file" in File::Slurp
       function.

   prepend_file
               use File::Slurp qw(prepend_file);
               prepend_file('/path/file', $header);
               prepend_file('/path/file', \@lines);
               prepend_file('/path/file', { binmode => ':raw'}, $bin_data);

               # equivalent to:
               use File::Slurp qw(read_file write_file);
               my $content = read_file('/path/file');
               my $new_content = "hahahaha";
               write_file('/path/file', $new_content . $content);

       The "prepend_file" function is the opposite of "append_file" in File::Slurp as it writes
       new contents to the beginning of the file instead of the end. It is a combination of
       "read_file" in File::Slurp and "write_file" in File::Slurp. It works by first using
       "read_file" to slurp in the file and then calling "write_file" with the new data and the
       existing file data.

       The first argument to "prepend_file" is the filename.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The options are passed through to the "write_file" in File::Slurp function. All options
       are described there.

       Only the "binmode" and "err_mode" options are supported. The "write_file" call has the
       "atomic" option set so you will always have a consistent file.

   read_dir
               use File::Slurp qw(read_dir);
               my @files = read_dir('/path/to/dir');
               # all files, even the dots
               my @files = read_dir('/path/to/dir', keep_dot_dot => 1);
               # keep the full file path
               my @paths = read_dir('/path/to/dir', prefix => 1);
               # scalar context
               my $files_ref = read_dir('/path/to/dir');

       This function returns a list of the filenames in the supplied directory. In list context,
       an array is returned, in scalar context, an array reference is returned.

       The first argument is the path to the directory to read.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The following options are available:

       o   err_mode

           The "err_mode" option has three possible values: "quiet", "carp", or the default,
           "croak". In "quiet" mode, all errors will be silent. In "carp" mode, all errors will
           be emitted as warnings. And, in "croak" mode, all errors will be emitted as
           exceptions. Take a look at Try::Tiny or Syntax::Keyword::Try to see how to catch
           exceptions.

       o   keep_dot_dot

           The "keep_dot_dot" option is a boolean option, defaulted to false (0).  Setting this
           option to true (1) will also return the "." and ".." files that are removed from the
           file list by default.

       o   prefix

           The "prefix" option is a boolean option, defaulted to false (0).  Setting this option
           to true (1) add the directory as a prefix to the file.  The directory and the filename
           are joined using "File::Spec->catfile()" to ensure the proper directory separator is
           used for your OS. See File::Spec.

   read_file
               use File::Slurp qw(read_file);
               my $text = read_file('/path/file');
               my $bin = read_file('/path/file', { binmode => ':raw' });
               my @lines = read_file('/path/file');
               my $lines_ref = read_file('/path/file', array_ref => 1);
               my $lines_ref = [ read_file('/path/file') ];

               # or we can read into a buffer:
               my $buffer;
               read_file('/path/file', buf_ref => \$buffer);

               # or we can set the block size for the read
               my $text_ref = read_file('/path/file', blk_size => 10_000_000, array_ref => 1);

               # or we can get a scalar reference
               my $text_ref = read_file('/path/file', scalar_ref => 1);

       This function reads in an entire file and returns its contents to the caller. In scalar
       context it returns the entire file as a single scalar. In list context it will return a
       list of lines (using the current value of $/ as the separator, including support for
       paragraph mode when it is set to '').

       The first argument is the path to the file to be slurped in.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The following options are available:

       o   array_ref

           The "array_ref" option is a boolean option, defaulted to false (0). Setting this
           option to true (1) will only have relevance if the "read_file" function is called in
           scalar context. When true, the "read_file" function will return a reference to an
           array of the lines in the file.

       o   binmode

           The "binmode" option is a string option, defaulted to empty (''). If you set the
           "binmode" option, then its value is passed to a call to "binmode" on the opened
           handle. You can use this to set the file to be read in binary mode, utf8, etc. See
           "perldoc -f binmode" for more.

           Please note that using binmode :utf8 with sysread (and thus read_file) has been
           deprecated in recent versions of perl.

       o   blk_size

           You can use this option to set the block size used when slurping from an already open
           handle (like "\*STDIN"). It defaults to 1MB.

       o   buf_ref

           The "buf_ref" option can be used in conjunction with any of the other options.  You
           can use this option to pass in a scalar reference and the slurped file contents will
           be stored in the scalar. This saves an extra copy of the slurped file and can lower
           RAM usage vs returning the file. It is usually the fastest way to read a file into a
           scalar.

       o   chomp

           The "chomp" option is a boolean option, defaulted to false (0). Setting this option to
           true (1) will cause each line to have its contents "chomp"ed.  This option works in
           list context or in scalar context with the "array_ref" option.

       o   err_mode

           The "err_mode" option has three possible values: "quiet", "carp", or the default,
           "croak". In "quiet" mode, all errors will be silent. In "carp" mode, all errors will
           be emitted as warnings. And, in "croak" mode, all errors will be emitted as
           exceptions. Take a look at Try::Tiny or Syntax::Keyword::Try to see how to catch
           exceptions.

       o   scalar_ref

           The "scalar_ref" option is a boolean option, defaulted to false (0). It only has
           meaning in scalar context. The return value will be a scalar reference to a string
           which is the contents of the slurped file. This will usually be faster than returning
           the plain scalar. It will also save memory as it will not make a copy of the file to
           return.

   rf
               use File::Slurp qw(rf);
               my $text = rf('/path/file');

       The "rf" function is simply a synonym for the "read_file" in File::Slurp function.

   slurp
               use File::Slurp qw(slurp);
               my $text = slurp('/path/file');

       The "slurp" function is simply a synonym for the "read_file" in File::Slurp function.

   wf
               use File::Slurp qw(wf);
               my $res = wf('/path/file', "Some text");

       The "wf" function is simply a synonym for the "write_file" in File::Slurp function.

   write_file
               use File::Slurp qw(write_file);
               write_file('/path/file', @data);
               write_file('/path/file', {append => 1}, @data);
               write_file('/path/file', {binmode => ':raw'}, $buffer);
               write_file('/path/file', \$buffer);
               write_file('/path/file', $buffer);
               write_file('/path/file', \@lines);
               write_file('/path/file', @lines);

               # binmode
               write_file('/path/file', {binmode => ':raw'}, @data);
               write_file('/path/file', {binmode => ':utf8'}, $utf_text);

               # buffered
               write_file('/path/file', {buf_ref => \$buffer});
               write_file('/path/file', \$buffer);
               write_file('/path/file', $buffer);

               # append
               write_file('/path/file', {append => 1}, @data);

               # no clobbering
               write_file('/path/file', {no_clobber => 1}, @data);

       This function writes out an entire file in one call. By default "write_file" returns 1
       upon successfully writing the file or "undef" if it encountered an error. You can change
       how errors are handled with the "err_mode" option.

       The first argument to "write_file" is the filename.

       The next argument(s) is either a hash reference or a flattened hash, "key => value" pairs.
       The following options are available:

       o   append

           The "append" option is a boolean option, defaulted to false (0). Setting this option
           to true (1) will cause the data to be be written at the end of the current file.
           Internally this sets the "sysopen" mode flag "O_APPEND".

           The "append_file" in File::Slurp function sets this option by default.

       o   atomic

           The "atomic" option is a boolean option, defaulted to false (0). Setting this option
           to true (1) will cause the file to be be written to in an atomic fashion. A temporary
           file name is created using "tempfile" in File::Temp.  After the file is closed it is
           renamed to the original file name (and "rename" is an atomic operation on most OSes).
           If the program using this were to crash in the middle of this, then the temporary file
           could be left behind.

       o   binmode

           The "binmode" option is a string option, defaulted to empty (''). If you set the
           "binmode" option, then its value is passed to a call to "binmode" on the opened
           handle. You can use this to set the file to be read in binary mode, utf8, etc. See
           "perldoc -f binmode" for more.

       o   buf_ref

           The "buf_ref" option is used to pass in a scalar reference which has the data to be
           written. If this is set then any data arguments (including the scalar reference
           shortcut) in @_ will be ignored.

       o   err_mode

           The "err_mode" option has three possible values: "quiet", "carp", or the default,
           "croak". In "quiet" mode, all errors will be silent. In "carp" mode, all errors will
           be emitted as warnings. And, in "croak" mode, all errors will be emitted as
           exceptions. Take a look at Try::Tiny or Syntax::Keyword::Try to see how to catch
           exceptions.

       o   no_clobber

           The "no_clobber" option is a boolean option, defaulted to false (0). Setting this
           option to true (1) will ensure an that existing file will not be overwritten.

       o   perms

           The "perms" option sets the permissions of newly-created files. This value is modified
           by your process's "umask" and defaults to 0666 (same as "sysopen").

           NOTE: this option is new as of File::Slurp version 9999.14.

EXPORT
       These are exported by default or with

               use File::Slurp qw(:std);
               # read_file write_file overwrite_file append_file read_dir

       These are exported with

               use File::Slurp qw(:edit);
               # edit_file edit_file_lines

       You can get all subs in the module exported with

               use File::Slurp qw(:all);

SEE ALSO
       o   File::Slurper - Provides a straightforward set of functions for the most common tasks
           of reading/writing text and binary files.

       o   Path::Tiny - Lightweight and comprehensive file handling, including simple methods for
           reading, writing, and editing text and binary files.

       o   Mojo::File - Similar to Path::Tiny for the Mojo toolkit, always works in bytes.

AUTHOR
       Uri Guttman, <uri AT stemsystems.com>

COPYRIGHT & LICENSE
       Copyright (c) 2003 Uri Guttman. All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

perl v5.30.3                                2020-07-27                           File::Slurp(3pm)

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