Skill Exec

Execute SKILL Code on Virtuoso

Run SKILL expressions via vcli skill exec and parse results.

Quick reference

# Arithmetic
vcli skill exec "1+2" --format json

# String operations
vcli skill exec 'strcat("hello" " " "world")' --format json

# List all libraries
vcli skill exec 'foreach(mapcar lib ddGetLibList() lib~>name)' --format json

# List cells in a library
vcli skill exec 'let((lib) lib=ddGetObj("myLib") foreach(mapcar c lib~>cells c~>name))' --format json

# Get cell views
vcli skill exec 'let((cell) cell=ddGetObj("myLib" "myCell") foreach(mapcar v cell~>views v~>name))' --format json

# Current cellview info
vcli skill exec 'let((cv) cv=geGetEditCellView() list(cv~>libName cv~>cellName cv~>viewName))' --format json

# Instance count
vcli skill exec 'let((cv) cv=geGetEditCellView() length(cv~>instances))' --format json

# Net names
vcli skill exec 'let((cv result n) cv=geGetEditCellView() result=nil n=0 foreach(net cv~>nets when(n<20 result=cons(net~>name result) n=n+1)) result)' --format json

# Schematic read (read-only)
vcli skill exec 'let((cv) cv=dbOpenCellViewByType("lib" "cell" "schematic" nil "r") sprintf(nil "inst=%d nets=%d" length(cv~>instances) length(cv~>nets)))' --format json

Multi-session usage

When multiple Virtuoso instances are running, specify the session explicitly:

vcli session list                                          # find alive session IDs
vcli --session meowu-meow-38371 skill exec 'getCurrentTime()'
export VB_SESSION=meowu-meow-38371                        # or set once for the shell
vcli skill exec 'getCurrentTime()'

Connection failure recovery

⚠️ Gotcha: --session <id> bypasses auto-filtering. If Virtuoso restarts, the session ID changes (new port → new ID). Explicitly specifying a dead session returns connection_failed: Connection refused (exit 1) even though other sessions are alive.

Recovery pattern (observed signal: exit 1 on skill exec followed by session list):

# 1. Stale session detected
vcli --session meowu-meow-32987 skill exec 'getCurrentTime()'
# → connection_failed: Connection refused (exit 1)

# 2. Purge dead session files and find new IDs
vcli session cleanup
vcli session list

# 3. Retry with the new session ID
vcli --session meowu-meow-38371 skill exec 'getCurrentTime()'

Multi-line input — skill eval --stdin

For snippets that span more than one line, or that contain characters painful to shell-quote (double quotes, parens, dollar signs), pipe the SKILL through stdin instead of stuffing it on the argv:

# argv form — fine for one-liners
vcli skill exec '1+2' --format json

# stdin form — survives any quoting problem; here-doc friendly
cat <<'EOF' | vcli skill eval --stdin --format json
let((x y)
    x = 1 + 2
    y = x * x
    y
)
EOF

Both skill exec and skill eval go through the daemon, but they differ in two ways that matter:

Rule of thumb: use eval --stdin whenever your SKILL has more than one top-level form, contains full-line comments, or defines a procedure then calls it.

⚠️ Gotcha — skill exec silently drops earlier forms. Inside the daemon's let(((__vb_r <code>)) ...), f1() f2() parses as "apply the result of f1() to the arguments of f2()" — only f2() runs. If you see printf(...) succeed but the side effect you expected from the prior statement is missing, switch to skill eval --stdin so the input is wrapped in progn(...).

CIW output vs return value

vcli skill exec (and eval) send the SKILL expression to Virtuoso for evaluation and capture the return value back into the JSON output field. They do not echo anything to the CIW window unless your expression does it itself with printf.

# Pure return value — CIW stays silent; vcli stdout gets "3"
vcli skill exec '1+2' --format json
# → {"status":"success","output":"3","errors":[],"warnings":[],...}
# CIW: (nothing)

# Both — printf shows in CIW, the let body's final form is the return value
vcli skill exec 'let((v) v=1+2 printf("1+2 = %d\n" v) v)' --format json
# → {"status":"success","output":"3",...}
# CIW: 1+2 = 3

When debugging a long expression, the printf(...) + final-form pattern is the cleanest way to inspect intermediate state without leaving CIW trace breadcrumbs that pollute later reads.

Attribution

The multi-line SKILL wrapping (progn(\n<code>\n)), --stdin input mode, and the CIW output vs return-value distinction are adapted from virtuoso-bridge-lite (MIT, 2026-06) — specifically cli.py::cli_eval, examples/01_virtuoso/basic/05_multiline_skill.py, and examples/01_virtuoso/basic/00_ciw_output_vs_return.py.

Important notes

• Use --format json for structured output (auto in pipe mode)
• Use --timeout N for long-running operations (default 30s)
• SKILL strings use ", escape with \" inside bash single quotes
• let blocks work for local variables; Ocean functions (simulator, design, run) must be at top level
• View names may not be standard schematic — check with v~>name not v~>viewName
• Always wrap slot access in let: let((cv) cv=geGetEditCellView() cv~>cellName) not geGetEditCellView()~>cellName — the latter crashes if no design is open