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samtools-index(1)	     Bioinformatics tools	     samtools-index(1)

NAME
       samtools	index -	indexes	SAM/BAM/CRAM files

SYNOPSIS
       samtools	index -M [-bc] [-m INT]	FILE FILE [FILE...]

       samtools	index [-bc] [-m	INT] aln.sam|aln.bam|aln.cram [out.index]

DESCRIPTION
       Index  coordinate-sorted	 BGZIP-compressed  SAM,	 BAM or	CRAM files for
       fast random access.  Note for SAM this only works if the	file has  been
       BGZF  compressed	 first.	 (The first synopsis with multiple input FILEs
       is only available with Samtools 1.16 or later.)

       This index is needed when region	arguments are used to  limit  samtools
       view and	similar	commands to particular regions of interest.

       When  only  one alignment file is being indexed,	the output index file-
       name can	be specified via -o or as shown	in the second synopsis.

       When no output filename is specified, for a CRAM	file  aln.cram,	 index
       file  aln.cram.crai  will  be  created;	for a BAM file aln.bam,	either
       aln.bam.bai or aln.bam.csi will be created; and for  a  compressed  SAM
       file  aln.sam.gz,  either aln.sam.gz.bai	or aln.sam.gz.csi will be cre-
       ated, depending on the index format selected.

       The BAI index format can	handle individual chromosomes up  to  512  Mbp
       (2^29  bases) in	length.	 If your input file might contain reads	mapped
       to positions greater than that, you will	need to	use a CSI index.

OPTIONS
       -b, --bai
	       Create a	BAI index.  This is currently the default when no for-
	       mat options are used.

       -c, --csi
	       Create a	CSI index.  By default,	the minimum interval size  for
	       the index is 2^14, which	is the same as the fixed value used by
	       the BAI format.

       -m, --min-shift INT
	       Create a	CSI index, with	a minimum interval size	of 2^INT.

       -M      Interpret  all  filename	arguments as alignment files to	be in-
	       dexed individually.  (Without -M, filename arguments are	inter-
	       preted solely as	per the	second synopsis.)

       -o, --output FILE
	       Write the output	index to FILE.	(Currently may	only  be  used
	       when exactly one	alignment file is being	indexed.)

       -@, --threads INT
	       Number  of  input/output	compression threads to use in addition
	       to main thread [0].

AUTHOR
       Written by Heng Li from the Sanger Institute.

SEE ALSO
       samtools(1), samtools-idxstats(1), samtools-view(1)

       Samtools	website: <http://www.htslib.org/>

samtools-1.21		       12 September 2024	     samtools-index(1)

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