Provided by: gromacs-data_4.6.5-1build1_all 
NAME
g_select - selects groups of atoms based on flexible textual selections
VERSION 4.6.5
SYNOPSIS
g_select -f traj.xtc -s topol.tpr -sf selection.dat -n index.ndx -os size.xvg -oc cfrac.xvg -oi index.dat
-om mask.dat -on index.ndx -[no]h -[no]version -nice int -b time -e time -dt time -xvg enum -[no]rmpbc
-[no]pbc -select string -selrpos enum -seltype enum -[no]dump -[no]norm -[no]cfnorm -resnr enum
DESCRIPTION
g_select writes out basic data about dynamic selections. It can be used for some simple analyses, or
the output can be combined with output from other programs and/or external analysis programs to calculate
more complex things. Any combination of the output options is possible, but note that -om only operates
on the first selection. -os is the default output option if none is selected.
With -os, calculates the number of positions in each selection for each frame. With -norm, the output
is between 0 and 1 and describes the fraction from the maximum number of positions (e.g., for selection
'resname RA and x 5' the maximum number of positions is the number of atoms in RA residues). With
-cfnorm, the output is divided by the fraction covered by the selection. -norm and -cfnorm can be
specified independently of one another.
With -oc, the fraction covered by each selection is written out as a function of time.
With -oi, the selected atoms/residues/molecules are written out as a function of time. In the output,
the first column contains the frame time, the second contains the number of positions, followed by the
atom/residue/molecule numbers. If more than one selection is specified, the size of the second group
immediately follows the last number of the first group and so on. With -dump, the frame time and the
number of positions is omitted from the output. In this case, only one selection can be given.
With -on, the selected atoms are written as a index file compatible with make_ndx and the analyzing
tools. Each selection is written as a selection group and for dynamic selections a group is written for
each frame.
For residue numbers, the output of -oi can be controlled with -resnr: number (default) prints the
residue numbers as they appear in the input file, while index prints unique numbers assigned to the
residues in the order they appear in the input file, starting with 1. The former is more intuitive, but
if the input contains multiple residues with the same number, the output can be less useful.
With -om, a mask is printed for the first selection as a function of time. Each line in the output
corresponds to one frame, and contains either 0/1 for each atom/residue/molecule possibly selected. 1
stands for the atom/residue/molecule being selected for the current frame, 0 for not selected. With
-dump, the frame time is omitted from the output.
FILES
-f traj.xtc Input, Opt.
Trajectory: xtc trr trj gro g96 pdb cpt
-s topol.tpr Input, Opt.
Structure+mass(db): tpr tpb tpa gro g96 pdb
-sf selection.dat Input, Opt.
Generic data file
-n index.ndx Input, Opt.
Index file
-os size.xvg Output, Opt.
xvgr/xmgr file
-oc cfrac.xvg Output, Opt.
xvgr/xmgr file
-oi index.dat Output, Opt.
Generic data file
-om mask.dat Output, Opt.
Generic data file
-on index.ndx Output, Opt.
Index file
OTHER OPTIONS
-[no]hno
Print help info and quit
-[no]versionno
Print version info and quit
-nice int 19
Set the nicelevel
-b time 0
First frame (ps) to read from trajectory
-e time 0
Last frame (ps) to read from trajectory
-dt time 0
Only use frame when t MOD dt = first time (ps)
-xvg enum xmgrace
xvg plot formatting: xmgrace, xmgr or none
-[no]rmpbcyes
Make molecules whole for each frame
-[no]pbcyes
Use periodic boundary conditions for distance calculation
-select string
Selection string (use 'help' for help). Note that the whole selection string will need to be quoted so
that your shell will pass it in as a string. Example: g_select -select '"Nearby water" resname SOL and
within 0.25 of group Protein'
-selrpos enum atom
Selection reference position: atom, res_com, res_cog, mol_com, mol_cog, whole_res_com,
whole_res_cog, whole_mol_com, whole_mol_cog, part_res_com, part_res_cog, part_mol_com,
part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com or dyn_mol_cog
-seltype enum atom
Default analysis positions: atom, res_com, res_cog, mol_com, mol_cog, whole_res_com,
whole_res_cog, whole_mol_com, whole_mol_cog, part_res_com, part_res_cog, part_mol_com,
part_mol_cog, dyn_res_com, dyn_res_cog, dyn_mol_com or dyn_mol_cog
-[no]dumpno
Do not print the frame time (-om, -oi) or the index size (-oi)
-[no]normno
Normalize by total number of positions with -os
-[no]cfnormno
Normalize by covered fraction with -os
-resnr enum number
Residue number output type: number or index
SEE ALSO
gromacs(7)
More information about GROMACS is available at <http://www.gromacs.org/>.
Mon 2 Dec 2013 g_select(1)