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Aho-Corasick string replacement utility

Project description

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Copyright (c) 2015 Will Roberts <>

Licensed under the MIT License (see file LICENSE.rst for details).

Search and replace on file(s), with matching on fixed strings.


fsed is written in Python; you can install it with pip:

pip install fsed



If one or more INPUT_FILEs are specified, fsed reads and concatenates these as its input; otherwise, fsed reads the standard input.


Set FMT to tsv or sed (default is sed) to specify the format of PATTERN_FILE.
Specifies that the program output should be written to OUTFILE. If this option is not used, fsed writes to standard output.
Makes fsed match only on word boundaries; this flag instructs fsed to append \b to the beginning and end of every pattern in PATTERN_FILE.
Sets whether fsed should process the input line by line or character by character; the default is --across-lines.
Indicates that fsed should try very hard to always find the longest matches on the input; this is very slow, and forces --by-line to be on.
Quiet operation, do not emit warnings.
Turns on debugging output.

Note: fsed runs even faster using PyPy:


Pattern File

PATTERN_FILE contains a list of patterns to search and replace in the input; each pattern is listed on a separate line. fsed supports two formats for specifying patterns. The default, sed, specifies strings and their replacements the way the sed utility does:


The character following the s character is the pattern delimiter, and can be any character (it does not have to be a forward slash).

The other format, tsv, specifies patterns using <TAB> characters as delimiters:


In this format, there must be only one <TAB> character per line.

Patterns can contain escape characters:

Backslash (\)
ASCII bell (BEL)
Word boundary
ASCII formfeed (FF)
ASCII linefeed (LF)
Carriage Return (CR)
Horizontal Tab (TAB)
ASCII vertical tab (VT)

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Files for fsed, version 0.5.0
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Filename, size fsed-0.5.0-py3-none-any.whl (18.1 kB) File type Wheel Python version py3 Upload date Hashes View
Filename, size fsed-0.5.0.tar.gz (558.9 kB) File type Source Python version None Upload date Hashes View

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