Provided by: cutadapt_4.2-1build1_all 
NAME
cutadapt - remove adapter sequences from high-throughput sequencing reads
SYNOPSIS
cutadapt -a ADAPTER [options] [-o output.fastq] input.fastq
For paired-end reads:
cutadapt -a ADAPT1 -A ADAPT2 [options] -o out1.fastq -p out2.fastq in1.fastq
in2.fastq
DESCRIPTION
Replace "ADAPTER" with the actual sequence of your 3' adapter. IUPAC wildcard characters
are supported. The reverse complement is *not* automatically searched. All reads from
input.fastq will be written to output.fastq with the adapter sequence removed. Adapter
matching is error-tolerant. Multiple adapter sequences can be given (use further -a
options), but only the best-matching adapter will be removed.
Input may also be in FASTA format. Compressed input and output is supported and
auto-detected from the file name (.gz, .xz, .bz2). Use the file name '-' for standard
input/output. Without the -o option, output is sent to standard output.
OPTIONS
--help show all command-line options
--version
show program's version number and exit
-h, --help
show this help message and exit
--debug
Print debugging information.
-f FORMAT, --format=FORMAT
Input file format; can be either 'fasta', 'fastq' or 'sra-fastq'. Ignored when
reading csfasta/qual files. Default: auto-detect from file name extension.
Finding adapters::
Parameters -a, -g, -b specify adapters to be removed from each read (or from the
first read in a pair if data is paired). If specified multiple times, only the best
matching adapter is trimmed (but see the --times option). When the special notation
'file:FILE' is used, adapter sequences are read from the given FASTA file.
-a ADAPTER, --adapter=ADAPTER
Sequence of an adapter ligated to the 3' end (paired data: of the first read). The
adapter and subsequent bases are trimmed. If a '$' character is appended
('anchoring'), the adapter is only found if it is a suffix of the read.
-g ADAPTER, --front=ADAPTER
Sequence of an adapter ligated to the 5' end (paired data: of the first read). The
adapter and any preceding bases are trimmed. Partial matches at the 5' end are
allowed. If a '^' character is prepended ('anchoring'), the adapter is only found
if it is a prefix of the read.
-b ADAPTER, --anywhere=ADAPTER
Sequence of an adapter that may be ligated to the 5' or 3' end (paired data: of the
first read). Both types of matches as described under -a und -g are allowed. If
the first base of the read is part of the match, the behavior is as with -g,
otherwise as with -a. This option is mostly for rescuing failed library
preparations - do not use if you know which end your adapter was ligated to!
-e ERROR_RATE, --error-rate=ERROR_RATE
Maximum allowed error rate (no. of errors divided by the length of the matching
region). Default: 0.1
--no-indels
Allow only mismatches in alignments. Default: allow both mismatches and indels
-n COUNT, --times=COUNT
Remove up to COUNT adapters from each read. Default: 1
-O MINLENGTH, --overlap=MINLENGTH
If the overlap between the read and the adapter is shorter than MINLENGTH, the read
is not modified. Reduces the no. of bases trimmed due to random adapter matches.
Default: 3
--match-read-wildcards
Interpret IUPAC wildcards in reads. Default: False
-N, --no-match-adapter-wildcards
Do not interpret IUPAC wildcards in adapters.
--no-trim
Match and redirect reads to output/untrimmed-output as usual, but do not remove
adapters.
--mask-adapter
Mask adapters with 'N' characters instead of trimming them.
Additional read modifications:
-u LENGTH, --cut=LENGTH
Remove bases from each read (first read only if paired). If LENGTH is positive,
remove bases from the beginning. If LENGTH is negative, remove bases from the end.
Can be used twice if LENGTHs have different signs.
-q [5'CUTOFF,]3'CUTOFF, --quality-cutoff=[5'CUTOFF,]3'CUTOFF
Trim low-quality bases from 5' and/or 3' ends of each read before adapter removal.
Applied to both reads if data is paired. If one value is given, only the 3' end is
trimmed. If two comma-separated cutoffs are given, the 5' end is trimmed with the
first cutoff, the 3' end with the second.
--nextseq-trim=3'CUTOFF
NextSeq-specific quality trimming (each read). Trims also dark cycles appearing as
high-quality G bases (EXPERIMENTAL).
--quality-base=QUALITY_BASE
Assume that quality values in FASTQ are encoded as ascii(quality + QUALITY_BASE).
This needs to be set to 64 for some old Illumina FASTQ files. Default: 33
--trim-n
Trim N's on ends of reads.
-x PREFIX, --prefix=PREFIX
Add this prefix to read names. Use {name} to insert the name of the matching
adapter.
-y SUFFIX, --suffix=SUFFIX
Add this suffix to read names; can also include {name}
--strip-suffix=STRIP_SUFFIX
Remove this suffix from read names if present. Can be given multiple times.
--length-tag=TAG
Search for TAG followed by a decimal number in the description field of the read.
Replace the decimal number with the correct length of the trimmed read. For
example, use --length-tag 'length=' to correct fields like 'length=123'.
Filtering of processed reads:
--discard-trimmed, --discard
Discard reads that contain an adapter. Also use -O to avoid discarding too many
randomly matching reads!
--discard-untrimmed, --trimmed-only
Discard reads that do not contain the adapter.
-m LENGTH, --minimum-length=LENGTH
Discard trimmed reads that are shorter than LENGTH. Reads that are too short even
before adapter removal are also discarded. In colorspace, an initial primer is not
counted. Default: 0
-M LENGTH, --maximum-length=LENGTH
Discard trimmed reads that are longer than LENGTH. Reads that are too long even
before adapter removal are also discarded. In colorspace, an initial primer is not
counted. Default: no limit
--max-n=COUNT
Discard reads with too many N bases. If COUNT is an integer, it is treated as the
absolute number of N bases. If it is between 0 and 1, it is treated as the
proportion of N's allowed in a read.
Output:
--quiet
Print only error messages.
-o FILE, --output=FILE
Write trimmed reads to FILE. FASTQ or FASTA format is chosen depending on input.
The summary report is sent to standard output. Use '{name}' in FILE to demultiplex
reads into multiple files. Default: write to standard output
--info-file=FILE
Write information about each read and its adapter matches into FILE. See the
documentation for the file format.
-r FILE, --rest-file=FILE
When the adapter matches in the middle of a read, write the rest (after the
adapter) into FILE.
--wildcard-file=FILE
When the adapter has N bases (wildcards), write adapter bases matching wildcard
positions to FILE. When there are indels in the alignment, this will often not be
accurate.
--too-short-output=FILE
Write reads that are too short (according to length specified by -m) to FILE.
Default: discard reads
--too-long-output=FILE
Write reads that are too long (according to length specified by -M) to FILE.
Default: discard reads
--untrimmed-output=FILE
Write reads that do not contain the adapter to FILE. Default: output to same file
as trimmed reads
Colorspace options:
-c, --colorspace
Enable colorspace mode: Also trim the color that is adjacent to the found adapter.
-d, --double-encode
Double-encode colors (map 0,1,2,3,4 to A,C,G,T,N).
-t, --trim-primer
Trim primer base and the first color (which is the transition to the first
nucleotide)
--strip-f3
Strip the _F3 suffix of read names
--maq, --bwa
MAQ- and BWA-compatible colorspace output. This enables -c, -d, -t, --strip-f3 and
-y '/1'.
--no-zero-cap
Do not change negative quality values to zero in colorspace data. By default, they
are since many tools have problems with negative qualities.
-z, --zero-cap
Change negative quality values to zero. This is enabled by default when
-c/--colorspace is also enabled. Use the above option to disable it.
Paired-end options:
The -A/-G/-B/-U options work like their -a/-b/-g/-u counterparts, but are applied
to the second read in each pair.
-A ADAPTER
3' adapter to be removed from second read in a pair.
-G ADAPTER
5' adapter to be removed from second read in a pair.
-B ADAPTER
5'/3 adapter to be removed from second read in a pair.
-U LENGTH
Remove LENGTH bases from second read in a pair (see --cut).
-p FILE, --paired-output=FILE
Write second read in a pair to FILE.
--pair-filter=(any|both)
Which of the reads in a paired-end read have to match the filtering criterion in
order for it to be filtered. Default: any
--interleaved
Read and write interleaved paired-end reads.
--untrimmed-paired-output=FILE
Write second read in a pair to this FILE when no adapter was found in the first
read. Use this option together with --untrimmed-output when trimming pairedend
reads. Default: output to same file as trimmed reads
--too-short-paired-output=FILE
Write second read in a pair to this file if pair is too short. Use together with
--too-short-output.
--too-long-paired-output=FILE
Write second read in a pair to this file if pair is too long. Use together with
--too-long-output.
SEE ALSO
See http://cutadapt.readthedocs.org/ for full documentation.
Citation
Marcel Martin. Cutadapt removes adapter sequences from high-throughput sequencing reads.
EMBnet.Journal, 17(1):10-12, May 2011. http://dx.doi.org/10.14806/ej.17.1.200
AUTHOR
This manpage was written by Andreas Tille for the Debian distribution and can be used for
any other usage of the program.