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:
• 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.
• 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.
• 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:
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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:
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
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