The following table summarizes the command line switches understood by the LTspice executable, XVIIx64.exe(XVIIx86.exe on 32-bit systems):
| Flag | Description |
| -alt | Set solver to Alternate. |
| -ascii | Use ASCII .raw files. Seriously degrades program performance. |
| -b | Run in batch mode. E.g. "XVIIx64.exe -b deck.cir" will leave the data in file deck.raw |
| -big | Start as a maximized window. |
| -encrypt | Encrypt a model library. For 3rd parties wishing to allow people to use libraries without revealing implementation details. Not used by Linear Technology Corporation models. |
| -FastAccess | Batch conversion of a binary .raw file to Fast Access format. |
| -FixUpSchematicFonts | Convert the font size field of very old user-authored schematic text to the modern default. |
| -FixUpSymbolFonts | Convert the font size field of very old user-authored symbols to the modern default. See Changelog.txt for application hints. |
| -ini <path> | Specify an .ini file to use other than %APPDATA%\LTspiceXVII.ini |
| -I<path> | Specify a path to insert in the symbol and file search paths. Must be the last specified option. No space between "-I" and <path> is allowed. |
| -max | Synonym for -big |
| -netlist | Batch conversion of a schematic to a netlist. |
| -norm | Set solver to Normal. |
| -PCBnetlist | Batch conversion of a schematic to a PCB format netlist. |
| -registry | Force LTspice to store user preferences, MRU, etc. in the registry instead of the file %APPDATA%\LTspiceXVII.ini |
| -Run | Start simulating the schematic opened on the command line without pressing the Run button. |
| -SOI | Allow MOSFET's to have up to 7 nodes even in subcircuit expansion. |
| -sync | Sync release |
| -uninstall | Executes one step of the uninstallation process. |
In addition to the above command line switches, LTspice accepts two environmental variables. If PASTE_OMEGA is set, the UNICODE capital omega symbol, ©, is pasted on the clipboard instead of "Ohm." If the environmental variable CAPITAL_KILO is set, LTspice understands you prefer an upper case metric multiplier for all multipliers greater than 1, not just those greater than 1000.