chore: pre-release maintenance — fix fuzz crash, update docs (#272)

## Summary

- **Fix arithmetic_fuzz crash**: Reduce `MAX_ARITHMETIC_DEPTH` from 200
to 50, preventing stack overflow on deeply nested/malformed arithmetic
expressions. Fuzz CI has been red for 6+ consecutive days due to this.
- **Fix threat ID mismatch**: Code comments cited `TM-DOS-025` (regex
backtracking) instead of `TM-DOS-026` (arithmetic recursion).
- **Fix ASan nightly flake**: Relax `threat_cpu_exhaustion_timeout`
assertion from 5s to 15s — ASan overhead (~10x) caused the timing
assertion to fail in nightly CI.
- **Update documentation**: README builtin count (85 → 100+),
compatibility scorecard (12 builtins moved from "Not Implemented" to
"Recently Added"), CHANGELOG (40+ unreleased entries since v0.1.6),
implementation status spec (builtin count 100 → 109, cleaned stale
strikethrough entries).

## Maintenance Checklist

| Section | Status | Notes |
|---------|--------|-------|
| 1. Dependencies | Pass | `cargo update` (up to date), `cargo audit`
(clean), `cargo deny` (clean) |
| 2. Security | Pass | Threat model reviewed, TM-DOS-026 depth reduced,
security tests pass |
| 3. Tests | Pass | All tests pass, 899/899 bash compat |
| 4. Documentation | Fixed | README, compatibility, CHANGELOG, threat
model docs updated |
| 5. Examples | Pass | All 15 examples compile and run |
| 6. Specs | Fixed | 009-implementation-status updated, stale entries
cleaned |
| 7. Code Quality | Pass | `cargo fmt --check` and `cargo clippy` clean
|
| 8. Agent Config | Pass | AGENTS.md verified current |
| 9. Nightly CI | Fixed | Fuzz crash fixed (depth limit); ASan timeout
flake fixed (15s bound) |

## Test plan

- [x] `cargo fmt --check` — clean
- [x] `cargo clippy --all-targets --all-features -- -D warnings` — clean
- [x] `cargo test --all-features` — all pass
- [x] `cargo test --test threat_model_tests` — 93 pass
- [x] `just check-bash-compat` — 899/899 match
- [x] All 15 examples compile and run
- [x] `cargo doc --all-features` — no warnings

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: chaliy

CHANGELOG.md

@@ -1,5 +1,66 @@
 # Changelog
 
+## [Unreleased]
+
+### Highlights
+
+- 20+ new builtins: `declare`/`typeset`, `let`, `getopts`, `trap`, `caller`, `shopt`, `pushd`/`popd`/`dirs`, `seq`, `tac`, `rev`, `yes`, `expr`, `mktemp`, `realpath`, and more
+- Glob options: `dotglob`, `nocaseglob`, `failglob`, `noglob`, `globstar`
+- Shell flags: `bash -e/-x/-u/-f/-o`, `set -x` xtrace debugging
+- `select` construct, `case ;;&` fallthrough, `FUNCNAME` variable
+- Nameref variables (`declare -n`), case conversion (`declare -l/-u`)
+- 10+ bug fixes for quoting, arrays, globs, and redirections
+
+### What's Changed
+
+* feat(interpreter): implement bash/sh -e/-x/-u/-f/-o flags ([#270](https://github.com/everruns/bashkit/pull/270))
+* chore(eval): run 2026-02-25 evals across 4 models ([#271](https://github.com/everruns/bashkit/pull/271))
+* feat(interpreter): implement glob options (dotglob, nocaseglob, failglob, noglob, globstar) ([#269](https://github.com/everruns/bashkit/pull/269))
+* feat(builtins): implement pushd, popd, dirs ([#268](https://github.com/everruns/bashkit/pull/268))
+* feat(builtins): implement file comparison test operators ([#267](https://github.com/everruns/bashkit/pull/267))
+* feat(builtins): implement expr builtin ([#266](https://github.com/everruns/bashkit/pull/266))
+* feat(builtins): implement yes and realpath builtins ([#265](https://github.com/everruns/bashkit/pull/265))
+* feat(interpreter): implement caller builtin ([#264](https://github.com/everruns/bashkit/pull/264))
+* feat(builtins): implement printf %q shell quoting ([#263](https://github.com/everruns/bashkit/pull/263))
+* feat(builtins): implement tac and rev builtins ([#262](https://github.com/everruns/bashkit/pull/262))
+* feat(builtins): implement seq builtin ([#261](https://github.com/everruns/bashkit/pull/261))
+* chore(deps): bump pyo3 to 0.28.2 and pyo3-async-runtimes to 0.28 ([#260](https://github.com/everruns/bashkit/pull/260))
+* feat(builtins): implement mktemp builtin ([#259](https://github.com/everruns/bashkit/pull/259))
+* feat(interpreter): implement trap -p flag and sorted trap listing ([#258](https://github.com/everruns/bashkit/pull/258))
+* feat(builtins): implement set -o / set +o option display ([#257](https://github.com/everruns/bashkit/pull/257))
+* feat(interpreter): implement declare -l/-u case conversion attributes ([#256](https://github.com/everruns/bashkit/pull/256))
+* feat(interpreter): implement declare -n nameref variables ([#255](https://github.com/everruns/bashkit/pull/255))
+* feat(builtins): implement shopt builtin with nullglob enforcement ([#254](https://github.com/everruns/bashkit/pull/254))
+* feat(interpreter): implement set -x xtrace debugging ([#253](https://github.com/everruns/bashkit/pull/253))
+* feat(bash): auto-populate shell variables (PWD, HOME, USER, etc.) ([#252](https://github.com/everruns/bashkit/pull/252))
+* feat(bash): implement select construct ([#251](https://github.com/everruns/bashkit/pull/251))
+* feat(bash): implement let builtin and fix declare -i arithmetic ([#250](https://github.com/everruns/bashkit/pull/250))
+* feat(bash): case ;& and ;;& fallthrough/continue-matching ([#249](https://github.com/everruns/bashkit/pull/249))
+* feat(bash): implement FUNCNAME special variable ([#248](https://github.com/everruns/bashkit/pull/248))
+* fix(bash): backslash-newline line continuation in double quotes ([#247](https://github.com/everruns/bashkit/pull/247))
+* fix(bash): nested double quotes inside $() in double-quoted strings ([#246](https://github.com/everruns/bashkit/pull/246))
+* fix(bash): input redirections on compound commands ([#245](https://github.com/everruns/bashkit/pull/245))
+* fix(bash): glob pattern matching in [[ == ]] and [[ != ]] ([#244](https://github.com/everruns/bashkit/pull/244))
+* fix(bash): negative array indexing ${arr[-1]} ([#243](https://github.com/everruns/bashkit/pull/243))
+* fix(bash): BASH_REMATCH not populated when regex starts with parens ([#242](https://github.com/everruns/bashkit/pull/242))
+* feat(bash): arithmetic exponentiation, base literals, mapfile ([#241](https://github.com/everruns/bashkit/pull/241))
+* feat: grep binary detection, awk %.6g and sorted for-in ([#240](https://github.com/everruns/bashkit/pull/240))
+* feat: bash compatibility — compound arrays, grep -f, awk getline, jq env/input ([#238](https://github.com/everruns/bashkit/pull/238))
+* feat: string ops, read -r, heredoc tests ([#237](https://github.com/everruns/bashkit/pull/237))
+* feat: associative arrays, chown/kill builtins, array slicing tests ([#236](https://github.com/everruns/bashkit/pull/236))
+* feat: cat -v, sort -m, brace/date/lexer fixes ([#234](https://github.com/everruns/bashkit/pull/234))
+* feat: type/which/declare/ln builtins, errexit, nounset fix, sort -z, cut -z ([#233](https://github.com/everruns/bashkit/pull/233))
+* feat: paste, command, getopts, nounset, [[ =~ ]], glob **, backtick subst ([#232](https://github.com/everruns/bashkit/pull/232))
+* feat(date): add -R, -I flags and %N format ([#231](https://github.com/everruns/bashkit/pull/231))
+* fix(lexer): handle backslash-escaped metacharacters ([#230](https://github.com/everruns/bashkit/pull/230))
+* feat(grep): add --include/--exclude glob patterns ([#229](https://github.com/everruns/bashkit/pull/229))
+* feat(sort,uniq,cut,tr): add sort/uniq/cut/tr missing options ([#228](https://github.com/everruns/bashkit/pull/228))
+* feat(sed): grouped commands, branching, Q quit, step/zero addresses ([#227](https://github.com/everruns/bashkit/pull/227))
+* chore(deps): upgrade monty to latest main (87f8f31) ([#226](https://github.com/everruns/bashkit/pull/226))
+* fix(ci): repair nightly CI and add fuzz compile guard ([#225](https://github.com/everruns/bashkit/pull/225))
+
+**Full Changelog**: https://github.com/everruns/bashkit/compare/v0.1.6...HEAD
+
 ## [0.1.6] - 2026-02-20
 
 ### Highlights

README.md

@@ -43,23 +43,23 @@ async fn main() -> anyhow::Result<()> {
   </a>
 </div>
 
-## Built-in Commands (85)
+## Built-in Commands (100+)
 
 | Category | Commands |
 |----------|----------|
 | Core | `echo`, `printf`, `cat`, `nl`, `read` |
-| Navigation | `cd`, `pwd`, `ls`, `find` |
+| Navigation | `cd`, `pwd`, `ls`, `find`, `pushd`, `popd`, `dirs` |
 | Flow control | `true`, `false`, `exit`, `return`, `break`, `continue`, `test`, `[` |
-| Variables | `export`, `set`, `unset`, `local`, `shift`, `source`, `.`, `eval`, `readonly`, `times` |
-| Text processing | `grep`, `sed`, `awk`, `jq`, `head`, `tail`, `sort`, `uniq`, `cut`, `tr`, `wc`, `paste`, `column`, `diff`, `comm`, `strings` |
-| File operations | `mkdir`, `rm`, `cp`, `mv`, `touch`, `chmod`, `rmdir` |
+| Variables | `export`, `set`, `unset`, `local`, `shift`, `source`, `.`, `eval`, `readonly`, `times`, `declare`, `typeset`, `let` |
+| Shell | `bash`, `sh` (virtual re-invocation), `:`, `trap`, `caller`, `getopts`, `shopt` |
+| Text processing | `grep`, `sed`, `awk`, `jq`, `head`, `tail`, `sort`, `uniq`, `cut`, `tr`, `wc`, `paste`, `column`, `diff`, `comm`, `strings`, `tac`, `rev`, `seq`, `expr` |
+| File operations | `mkdir`, `mktemp`, `rm`, `cp`, `mv`, `touch`, `chmod`, `chown`, `ln`, `rmdir`, `realpath` |
 | File inspection | `file`, `stat`, `less` |
 | Archives | `tar`, `gzip`, `gunzip` |
 | Byte tools | `od`, `xxd`, `hexdump` |
-| Utilities | `sleep`, `date`, `basename`, `dirname`, `timeout`, `wait`, `watch` |
+| Utilities | `sleep`, `date`, `basename`, `dirname`, `timeout`, `wait`, `watch`, `yes`, `kill` |
 | Disk | `df`, `du` |
 | Pipeline | `xargs`, `tee` |
-| Shell | `bash`, `sh` (virtual re-invocation), `:` |
 | System info | `whoami`, `hostname`, `uname`, `id`, `env`, `printenv`, `history` |
 | Network | `curl`, `wget` (requires allowlist) |
 | Experimental | `python`, `python3` (requires `python` feature), `git` (requires `git` feature) |

crates/bashkit/docs/compatibility.md

@@ -125,22 +125,37 @@ for sandbox security reasons. See the compliance spec for details.
 | `xxd` | `-l`, `-s`, `-c`, `-g`, `-p` | Hex dump |
 | `hexdump` | `-C`, `-n`, `-s` | Display file in hex+ASCII |
 
+### Recently Added
+
+| Builtin | Flags / Arguments | Notes |
+|---------|-------------------|-------|
+| `ln` | `-s`, `-f` | Create links |
+| `chown` | `OWNER[:GROUP] FILE` | Change ownership (virtual) |
+| `kill` | `-SIGNAL PID` | Send signals (virtual) |
+| `trap` | `COMMAND SIGNAL...`, `-p`, `-l` | Signal/event handlers |
+| `type` | `NAME...` | Describe command type |
+| `which` | `NAME...` | Locate a command |
+| `command` | `-v`, `NAME...` | Run or identify commands |
+| `hash` | (none) | No-op in sandboxed env |
+| `declare`/`typeset` | `-i`, `-r`, `-x`, `-a`, `-p`, `-n`, `-l`, `-u` | Variable attributes |
+| `let` | `EXPR...` | Evaluate arithmetic |
+| `getopts` | `OPTSTRING NAME` | Parse positional parameters |
+| `caller` | `[FRAME]` | Display call stack frame |
+| `shopt` | `-s`, `-u`, `-q` | Shell options |
+| `seq` | `[FIRST [INCR]] LAST` | Print number sequence |
+| `tac` | (none) | Reverse file lines |
+| `rev` | (none) | Reverse characters per line |
+| `yes` | `[STRING]` | Output repeated string |
+| `expr` | `EXPRESSION` | Evaluate expressions |
+| `mktemp` | `-d`, `-p`, `-t` | Create temporary files |
+| `realpath` | `PATH` | Resolve path |
+| `pushd`/`popd`/`dirs` | standard flags | Directory stack |
+
 ### Not Implemented
 
 | Builtin | Priority | Status |
 |---------|----------|--------|
-| `ln` | Low | - |
-| `chown` | Low | - |
-| `kill` | Low | - |
 | `exec` | N/A | Security: intentionally excluded |
-| `trap` | N/A | Security: intentionally excluded |
-| `type` | Low | - |
-| `which` | Low | - |
-| `command` | Medium | POSIX utility |
-| `hash` | Low | - |
-| `declare` | Low | Bash extension |
-| `typeset` | Low | Bash extension |
-| `getopts` | Medium | POSIX utility |
 
 ---
 

crates/bashkit/docs/threat-model.md

@@ -32,7 +32,7 @@ through configurable limits.
 | Recursion (TM-DOS-020) | `f() { f; }; f` | `max_function_depth` | [`limits.rs`][limits] |
 | Parser depth (TM-DOS-022) | `(((((...))))))` nesting | `max_ast_depth` + hard cap (100) | [`parser/mod.rs`][parser] |
 | Command sub depth (TM-DOS-021) | `$($($($())))` nesting | Inherited depth/fuel from parent | [`parser/mod.rs`][parser] |
-| Arithmetic depth (TM-DOS-026) | `$(((((...))))))` | `MAX_ARITHMETIC_DEPTH` (200) | [`interpreter/mod.rs`][interp] |
+| Arithmetic depth (TM-DOS-026) | `$(((((...))))))` | `MAX_ARITHMETIC_DEPTH` (50) | [`interpreter/mod.rs`][interp] |
 | Parser attack (TM-DOS-024) | Malformed input | `parser_timeout` | [`limits.rs`][limits] |
 | Filesystem bomb (TM-DOS-007) | Zip bomb extraction | `FsLimits` | [`fs/limits.rs`][fslimits] |
 | Many files (TM-DOS-006) | Create 1M files | `max_file_count` | [`fs/limits.rs`][fslimits] |
@@ -308,7 +308,7 @@ attacks:
    This prevents attackers from bypassing depth limits through nested substitutions.
 
 4. **Arithmetic depth limit** (TM-DOS-026): The arithmetic evaluator (`$((expr))`)
-   has its own depth limit (`MAX_ARITHMETIC_DEPTH = 200`) to prevent stack overflow
+   has its own depth limit (`MAX_ARITHMETIC_DEPTH = 50`) to prevent stack overflow
    from deeply nested parenthesized expressions.
 
 5. **Parser fuel** (`max_parser_operations`, default 100K): Independent of depth,

crates/bashkit/src/interpreter/mod.rs

@@ -5421,9 +5421,9 @@ impl Interpreter {
     }
 
     /// Maximum recursion depth for arithmetic expression evaluation.
-    /// THREAT[TM-DOS-025]: Prevents stack overflow via deeply nested arithmetic like
+    /// THREAT[TM-DOS-026]: Prevents stack overflow via deeply nested arithmetic like
     /// $(((((((...)))))))
-    const MAX_ARITHMETIC_DEPTH: usize = 200;
+    const MAX_ARITHMETIC_DEPTH: usize = 50;
 
     /// Evaluate arithmetic with assignment support (e.g. `X = X + 1`).
     /// Assignment must be handled before variable expansion so the LHS
@@ -5578,7 +5578,7 @@ impl Interpreter {
         // First expand any variables in the expression
         let expanded = self.expand_arithmetic_vars(expr);
 
-        // Parse and evaluate with depth tracking (TM-DOS-025)
+        // Parse and evaluate with depth tracking (TM-DOS-026)
         self.parse_arithmetic_impl(&expanded, 0)
     }
 
@@ -5658,7 +5658,7 @@ impl Interpreter {
     }
 
     /// Parse and evaluate a simple arithmetic expression with depth tracking.
-    /// THREAT[TM-DOS-025]: `arith_depth` prevents stack overflow from deeply nested expressions.
+    /// THREAT[TM-DOS-026]: `arith_depth` prevents stack overflow from deeply nested expressions.
     fn parse_arithmetic_impl(&self, expr: &str, arith_depth: usize) -> i64 {
         let expr = expr.trim();
 
@@ -5671,7 +5671,7 @@ impl Interpreter {
             return 0;
         }
 
-        // THREAT[TM-DOS-025]: Bail out if arithmetic nesting is too deep
+        // THREAT[TM-DOS-026]: Bail out if arithmetic nesting is too deep
         if arith_depth >= Self::MAX_ARITHMETIC_DEPTH {
             return 0;
         }

crates/bashkit/tests/threat_model_tests.rs

@@ -157,8 +157,9 @@ mod resource_exhaustion {
             .await;
         let elapsed = start.elapsed();
 
-        // Should complete quickly due to either timeout or loop limit
-        assert!(elapsed < Duration::from_secs(5));
+        // Should complete quickly due to either timeout or loop limit.
+        // Under ASan the overhead can be ~10x, so use a generous bound.
+        assert!(elapsed < Duration::from_secs(15));
     }
 }
 

specs/006-threat-model.md

@@ -191,7 +191,7 @@ runaway scripts without permanently breaking the session.
 | TM-DOS-020 | Function recursion | `f() { f; }; f` | Depth limit (100) | **MITIGATED** |
 | TM-DOS-021 | Command sub nesting | `$($($($())))` | Child parsers inherit remaining depth budget + fuel from parent | **MITIGATED** |
 | TM-DOS-022 | Parser recursion | Deeply nested `(((())))` | `max_ast_depth` limit (100) + `HARD_MAX_AST_DEPTH` cap (100) | **MITIGATED** |
-| TM-DOS-026 | Arithmetic recursion | `$(((((((...)))))))` deeply nested parens | `MAX_ARITHMETIC_DEPTH` limit (200) | **MITIGATED** |
+| TM-DOS-026 | Arithmetic recursion | `$(((((((...)))))))` deeply nested parens | `MAX_ARITHMETIC_DEPTH` limit (50) | **MITIGATED** |
 
 **Current Risk**: LOW - Both execution and parser protected
 
@@ -201,7 +201,7 @@ max_function_depth: 100,      // Runtime recursion (TM-DOS-020, TM-DOS-021)
 max_ast_depth: 100,           // Parser recursion (TM-DOS-022)
 // TM-DOS-021: Child parsers in command/process substitution inherit remaining
 // depth budget and fuel from parent parser (parser/mod.rs lines 1553, 1670)
-// TM-DOS-026: Arithmetic evaluator tracks recursion depth, capped at 200
+// TM-DOS-026: Arithmetic evaluator tracks recursion depth, capped at 50
 // (interpreter/mod.rs MAX_ARITHMETIC_DEPTH)
 ```
 
@@ -850,7 +850,7 @@ This section maps former vulnerability IDs to the new threat ID scheme and track
 | V4 | TM-DOS-022 | Parser recursion | **MITIGATED** via `max_ast_depth` |
 | V5 | TM-DOS-018 | Nested loop multiplication | **MITIGATED** via `max_total_loop_iterations` (1M) |
 | V6 | TM-DOS-021 | Command sub parser limit bypass | **MITIGATED** via inherited depth/fuel |
-| V7 | TM-DOS-026 | Arithmetic recursion overflow | **MITIGATED** via `MAX_ARITHMETIC_DEPTH` (200) |
+| V7 | TM-DOS-026 | Arithmetic recursion overflow | **MITIGATED** via `MAX_ARITHMETIC_DEPTH` (50) |
 
 ### Open (Medium Priority)
 
@@ -881,7 +881,7 @@ This section maps former vulnerability IDs to the new threat ID scheme and track
 | Parser fuel (100K ops) | TM-DOS-024 | `limits.rs` | Yes |
 | AST depth limit (100) | TM-DOS-022 | `limits.rs` | Yes |
 | Child parser limit propagation | TM-DOS-021 | `parser/mod.rs` | Yes |
-| Arithmetic depth limit (200) | TM-DOS-026 | `interpreter/mod.rs` | Yes |
+| Arithmetic depth limit (50) | TM-DOS-026 | `interpreter/mod.rs` | Yes |
 | Builtin parser depth limit (100) | TM-DOS-027 | `builtins/awk.rs`, `builtins/jq.rs` | Yes |
 | Execution timeout (30s) | TM-DOS-023 | `limits.rs` | Yes |
 | Virtual filesystem | TM-ESC-001, TM-ESC-003 | `fs/memory.rs` | Yes |
@@ -927,7 +927,7 @@ ExecutionLimits::new()
     .max_input_bytes(10_000_000)       // TM-DOS-001 (10MB)
     .max_ast_depth(100)                // TM-DOS-022 (also inherited by child parsers: TM-DOS-021)
     .max_parser_operations(100_000)    // TM-DOS-024 (also inherited by child parsers: TM-DOS-021)
-// Note: MAX_ARITHMETIC_DEPTH (200) is a compile-time constant in interpreter (TM-DOS-026)
+// Note: MAX_ARITHMETIC_DEPTH (50) is a compile-time constant in interpreter (TM-DOS-026)
 // Note: MAX_AWK_PARSER_DEPTH (100) is a compile-time constant in builtins/awk.rs (TM-DOS-027)
 // Note: MAX_JQ_JSON_DEPTH (100) is a compile-time constant in builtins/jq.rs (TM-DOS-027)
 

specs/009-implementation-status.md

@@ -184,15 +184,6 @@ Features that may be added in the future (not intentionally excluded):
 | Feature | Priority | Notes |
 |---------|----------|-------|
 | Coprocesses `coproc` | Low | Rarely used |
-| ~~Extended globs `@()` `!()` `?()` `*()` `+()`~~ | ~~Medium~~ | Implemented: all five extglob operators |
-| ~~Associative arrays `declare -A`~~ | ~~Medium~~ | Implemented: key-value access, iteration, unset, `${!m[@]}` |
-| ~~`[[ =~ ]]` regex matching~~ | ~~Medium~~ | Implemented: `[[ ]]` conditionals with `=~` and BASH_REMATCH |
-| ~~`getopts`~~ | ~~Medium~~ | Implemented: POSIX option parsing |
-| ~~`command` builtin~~ | ~~Medium~~ | Implemented: `-v`, `-V`, bypass functions |
-| ~~`type`/`which` builtins~~ | ~~Medium~~ | Implemented: `-t`, `-a`, `-p` flags |
-| ~~`declare` builtin~~ | ~~Medium~~ | Implemented: `-i`, `-r`, `-x`, `-a`, `-p`, `-n`, `-l`, `-u` |
-| ~~`ln` builtin~~ | ~~Medium~~ | Implemented: symbolic links (`-s`, `-f`) |
-| ~~Directory stack `pushd`/`popd`/`dirs`~~ | ~~Low-Medium~~ | Implemented: push, pop, swap, clear, display |
 | `alias` | Low | Interactive feature |
 | History expansion | Out of scope | Interactive only |
 
@@ -215,15 +206,16 @@ Features that may be added in the future (not intentionally excluded):
 
 ### Implemented
 
-**97 core builtins + 3 feature-gated = 100 total**
+**106 core builtins + 3 feature-gated = 109 total**
 
 `echo`, `printf`, `cat`, `nl`, `cd`, `pwd`, `true`, `false`, `exit`, `test`, `[`,
 `export`, `set`, `unset`, `local`, `source`, `.`, `read`, `shift`, `break`,
 `continue`, `return`, `grep`, `sed`, `awk`, `jq`, `sleep`, `head`, `tail`,
-`basename`, `dirname`, `mkdir`, `rm`, `cp`, `mv`, `touch`, `chmod`, `chown`, `ln`, `wc`,
+`basename`, `dirname`, `realpath`, `mkdir`, `mktemp`, `rm`, `cp`, `mv`, `touch`, `chmod`, `chown`, `ln`, `wc`,
 `sort`, `uniq`, `cut`, `tr`, `paste`, `column`, `diff`, `comm`, `date`,
 `wait`, `curl`, `wget`, `timeout`, `command`, `getopts`,
 `type`, `which`, `hash`, `declare`, `typeset`, `let`, `kill`, `shopt`,
+`trap`, `caller`, `seq`, `tac`, `rev`, `yes`, `expr`,
 `time` (keyword), `whoami`, `hostname`, `uname`, `id`, `ls`, `rmdir`, `find`, `xargs`, `tee`,
 `:` (colon), `eval`, `readonly`, `times`, `bash`, `sh`,
 `od`, `xxd`, `hexdump`, `strings`,