add subshells, here-documents and redirections/pipes for control structures
- control structures can have redirections (while read l; do ...; done
< file), which apply to all commands in them; they run in the shell
- in pipes and in the background they run in a subshell (cmd | while
read l; do ...; done, for ...; done &, a && b &)
- ( list ) subshells; ( and ) are operators now
- here-documents <<EOF, <<-EOF, <<'EOF' and here-strings <<<word
- redirections of source apply to the commands of the file
- fix non-ASCII characters in quotes being mangled ('für')
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Florian WaltherandClaude Opus 5.5 committed
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commit
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@@ -191,14 +191,14 @@ func tokenize(input string) ([]token, error) {
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if quote == '"' && !strings.ContainsRune("$\"\\`", rune(ch)) {
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literal("\\")
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}
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literal(string(ch))
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literal(input[i : i+1])
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inWord = true
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escaped = false
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case quote == '\'':
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if ch == '\'' {
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quote = 0
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} else {
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literal(string(ch))
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literal(input[i : i+1])
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}
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case ch == '\\':
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startRaw(i)
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@@ -263,7 +263,7 @@ func tokenize(input string) ([]token, error) {
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if ch == '"' {
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quote = 0
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} else {
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literal(string(ch))
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literal(input[i : i+1])
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}
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case ch == '"' || ch == '\'':
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startRaw(i)
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@@ -306,6 +306,10 @@ func tokenize(input string) ([]token, error) {
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}
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t := token{op: string(ch), fd: fd}
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switch {
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case strings.HasPrefix(input[i:], "<<<"):
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// <<<word: the word (and a newline) is the input
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t.op = "<<<"
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i += 2
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case ch == '>' && i+1 < len(input) && input[i+1] == '>':
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t.op = ">>"
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i++
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@@ -1418,27 +1422,8 @@ func execInput(input string) error {
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// execCommand executes a pipeline of simple commands with redirections, in
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// the background if background is set.
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func execCommand(input string, background bool) error {
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// Brace expansion comes first, so that its results are expanded further
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substStatus = 0
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input, err := expandBraceWords(input)
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if err != nil {
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return err
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}
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// Split the input into words and operators, expanding variables and ~ on
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// the way.
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tokens, err := tokenize(input)
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var (
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synErr syntaxError
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statusErr statusError
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)
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if errors.As(err, &synErr) || errors.As(err, &statusErr) {
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return err
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}
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if err != nil {
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return fmt.Errorf("invalid input: %w", err)
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}
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stages, err := parsePipeline(tokens)
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stages, err := expandStages(input)
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if err != nil {
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return err
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}
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@@ -1456,19 +1441,62 @@ func execCommand(input string, background bool) error {
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return runPipeline(stages, strings.TrimSpace(input), background)
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}
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// redirect is a redirection of a simple command, e.g. 2>>file or 2>&1.
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type redirect struct {
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op string // <, >, >>, &>, &>>, >& or <&
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fd int // the redirected file descriptor
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dup int // the target file descriptor of >& and <&
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file string // the file name for all other operators
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// expandStages expands the text of a pipeline of simple commands and splits
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// it into its stages.
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func expandStages(input string) ([]stage, error) {
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// Brace expansion comes first, so that its results are expanded further
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input, err := expandBraceWords(input)
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if err != nil {
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return nil, err
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}
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// Split the input into words and operators, expanding variables and ~ on
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// the way.
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tokens, err := tokenize(input)
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var (
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synErr syntaxError
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statusErr statusError
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)
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if errors.As(err, &synErr) || errors.As(err, &statusErr) {
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return nil, err
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}
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if err != nil {
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return nil, fmt.Errorf("invalid input: %w", err)
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}
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return parsePipeline(tokens)
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}
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// stage is a simple command of a pipeline.
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// openRedirections expands and opens the redirections of a compound command
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// and returns the resulting stdin, stdout and stderr, and the files to close
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// afterwards.
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func openRedirections(text string) ([3]*os.File, []*os.File, error) {
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fds := [3]*os.File{stdio(0), stdio(1), stdio(2)}
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stages, err := expandStages(text)
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if err != nil {
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return fds, nil, err
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}
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if len(stages) != 1 || len(stages[0].args) > 0 || len(stages[0].assigns) > 0 {
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return fds, nil, syntaxError(text)
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}
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opened, err := applyRedirects(&fds, stages[0].redirects)
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return fds, opened, err
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}
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// redirect is a redirection of a simple command, e.g. 2>>file or 2>&1.
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type redirect struct {
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op string // <, >, >>, &>, &>>, >&, <& or <<<
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fd int // the redirected file descriptor
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dup int // the target file descriptor of >& and <&
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file string // the file name for all other operators (the text for <<<)
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}
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// stage is a simple command of a pipeline, or a script that runs in a
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// subshell (a compound command in a pipeline or in the background).
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type stage struct {
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assigns []string // name=value before the command name
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args []string
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redirects []redirect
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script string
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}
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// parsePipeline groups tokens into the stages of a pipeline.
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@@ -1505,6 +1533,11 @@ func parsePipeline(tokens []token) ([]stage, error) {
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return nil, syntaxError(next.op)
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}
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i++
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if t.op == "<<<" {
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// A here-string is not expanded as a pattern
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cur.redirects = append(cur.redirects, redirect{op: t.op, fd: t.fd, file: tokens[i].word})
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continue
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}
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files := expandWord(tokens[i])
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if len(files) > 1 {
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return nil, fmt.Errorf("%s: ambiguous redirect", sanitize(tokens[i].word))
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@@ -1621,18 +1654,22 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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err = statusError(substStatus)
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}
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}
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if err != nil || len(st.args) == 0 {
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if err != nil || len(st.args) == 0 && st.script == "" {
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// A command without arguments only creates or truncates the files
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closeOwned()
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return finishedProc(err)
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}
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fn, isFunc := functions[st.args[0]]
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var fn *funcDef
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isFunc := false
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if st.script == "" {
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fn, isFunc = functions[st.args[0]]
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}
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if isFunc && !inPipeline && !background {
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defer closeOwned()
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return finishedProc(callFunction(fn, st.args, fds, st.assigns))
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}
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if builtin, ok := builtins[st.args[0]]; !isFunc && ok {
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if builtin, ok := builtins[firstArg(st.args)]; !isFunc && st.script == "" && ok {
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switch {
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case inPipeline && builtin.changesState:
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closeOwned()
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@@ -1641,10 +1678,11 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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closeOwned()
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return finishedProc(fmt.Errorf("%s: cannot be run in the background", st.args[0]))
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}
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shellStderr := stdio(2)
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run := func() error {
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defer closeOwned()
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err := runBuiltin(st.args, fds[0], fds[1])
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if err != nil && fds[2] != stdio(2) {
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if err != nil && fds[2] != shellStderr {
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// Report the error where stderr is redirected to
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fmt.Fprintln(fds[2], "gosh:", err)
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return statusError(1)
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@@ -1652,8 +1690,12 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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return err
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}
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if !inPipeline && !background {
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// name=value before a builtin applies only while it runs
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// name=value before a builtin applies only while it runs, its
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// redirections also to the commands it runs (source file > out)
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defer setTemporarily(st.assigns)()
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saved := ioOverride
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ioOverride = fds
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defer func() { ioOverride = saved }()
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return finishedProc(run())
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}
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p := &proc{done: make(chan error, 1)}
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@@ -1662,7 +1704,13 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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}
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var cmd *exec.Cmd
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if isFunc {
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if st.script != "" {
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cmd, err = subshellCommand(st.script, positional)
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if err != nil {
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closeOwned()
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return finishedProc(err)
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}
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} else if isFunc {
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// A function in a pipeline or in the background runs in a subshell
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cmd, err = subshellCommand(`"$@"`, st.args)
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if err != nil {
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@@ -1695,7 +1743,7 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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// The child has its own copies of the files now
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closeOwned()
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if errors.Is(err, exec.ErrNotFound) {
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err = fmt.Errorf("%s: %w", sanitize(st.args[0]), errCommandNotFound)
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err = fmt.Errorf("%s: %w", sanitize(firstArg(st.args)), errCommandNotFound)
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}
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if err != nil {
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return finishedProc(err)
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@@ -1710,6 +1758,13 @@ func startStage(st stage, stdin, stdout *os.File, j *job, inPipeline, background
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return &proc{cmd: cmd}
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}
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func firstArg(args []string) string {
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if len(args) == 0 {
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return ""
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}
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return args[0]
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}
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// setTemporarily sets the variables of the assignments and returns a
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// function that restores the previous values.
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func setTemporarily(assigns []string) func() {
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@@ -1758,6 +1813,16 @@ func applyRedirects(fds *[3]*os.File, redirects []redirect) ([]*os.File, error)
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continue
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}
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if r.op == "<<<" {
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f, err := hereFile(r.file + "\n")
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if err != nil {
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return fail(err)
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}
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opened = append(opened, f)
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fds[r.fd] = f
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continue
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}
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flags := os.O_WRONLY | os.O_CREATE | os.O_TRUNC
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switch r.op {
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case "<":
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@@ -1783,6 +1848,26 @@ func applyRedirects(fds *[3]*os.File, redirects []redirect) ([]*os.File, error)
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return opened, nil
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}
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// hereFile returns a file to read content from: a temporary file that is
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// already removed (like bash does for here-documents), so that large inputs
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// work and nothing is left behind.
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func hereFile(content string) (*os.File, error) {
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f, err := os.CreateTemp("", "gosh-here-*")
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if err != nil {
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return nil, err
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}
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os.Remove(f.Name())
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if _, err := f.WriteString(content); err != nil {
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f.Close()
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return nil, err
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}
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if _, err := f.Seek(0, io.SeekStart); err != nil {
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f.Close()
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return nil, err
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}
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return f, nil
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}
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// builtins lists the built-in commands. Commands that change the state of
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// the shell cannot be used in a pipeline, since there they would run
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// concurrently (sh runs them in a subshell where they have no effect).
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@@ -2021,12 +2106,16 @@ Features:
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a || b (b only if a failed); $? is the exit status of the last command
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- Control structures: if cmd; then ...; elif cmd; then ...; else ...; fi,
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for x in words; do ...; done, while cmd; do ...; done, until ...,
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case word in pattern|pattern) ...;; esac, { cmd; cmd; } groups;
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! cmd negates the status; they can span several lines (prompt "> ")
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case word in pattern|pattern) ...;; esac, { cmd; cmd; } groups,
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( cmd; cmd ) subshells; ! cmd negates the status; they can span
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several lines (prompt "> "), have redirections (done < file) and can
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be used in pipes (| while read l; do ...; done) and with &
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- Functions: name() { ...; } (or function name { ...; }); the arguments
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are $1, $2, ...; in pipes, & and $(...) they run in a subshell
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- Pipes (a | b) and redirections: < file, > file, >> file, 2> file,
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2>> file, 2>&1, >&2, &> file (stdout and stderr), &>> file
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2>> file, 2>&1, >&2, &> file (stdout and stderr), &>> file,
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<<EOF here-documents (<<-EOF strips tabs, <<'EOF' expands nothing),
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<<<word here-strings
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- Job control: command & runs in the background, Ctrl+Z stops the
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foreground job; jobs, fg, bg and wait manage the jobs
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- Aliases replace the first word of a command in interactive shells
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