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(zsh.info)Complex Commands

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Complex Commands
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A _complex command_ in zsh is one of the following:

if LIST then LIST [ elif LIST then LIST ] ... [ else LIST ] fi
     The if LIST is executed, and if it returns a zero exit status, the
     then LIST is executed.  Otherwise, the elif LIST is executed and
     if its value is zero, the then LIST is executed.  If each elif
     LIST returns nonzero, the else LIST is executed.

for NAME [ in WORD ... TERM ] do LIST done
     where TERM is at least one newline or ;.  Expand the list of
     WORDs, and set the parameter NAME to each of them in turn,
     executing LIST each time.  If the in WORD is omitted, use the
     positional parameters instead of the WORDs.

for (( [EXPR1] ; [EXPR2] ; [EXPR3] )) do LIST done
     The arithmetic expression EXPR1 is evaluated first (see Note:
     Arithmetic Evaluation).  The arithmetic expression EXPR2 is
     repeatedly evaluated until it evaluates to zero and when non-zero,
     LIST is executed and the arithmetic expression EXPR3 evaluated.
     If any expression is omitted, then it behaves as if it evaluated
     to 1.

while LIST do LIST done
     Execute the do LIST as long as the while LIST returns a zero exit
     status.

until LIST do LIST done
     Execute the do LIST as long as until LIST returns a nonzero exit
     status.

repeat WORD do LIST done
     WORD is expanded and treated as an arithmetic expression, which
     must evaluate to a number N.  LIST is then executed N times.

case WORD in [ [(] PATTERN [ | PATTERN ] ... ) LIST (;;|;&) ] ... esac
     Execute the LIST associated with the first PATTERN that matches
     WORD, if any.  The form of the patterns is the same as that used
     for filename generation.  See Note: Filename Generation.  If the
     LIST that is executed is terminated with ;& rather than ;;, the
     following list is also executed.  This continues until either a
     list is terminated with ;; or the esac is reached.

select NAME [ in WORD ... TERM ] do LIST done
     where TERM is one or more newline or ; to terminate the WORDs.
     Print the set of WORDs, each preceded by a number.  If the in WORD
     is omitted, use the positional parameters.  The PROMPT3 prompt is
     printed and a line is read from the line editor if the shell is
     interactive and that is active, or else standard input.  If this
     line consists of the number of one of the listed WORDs, then the
     parameter NAME is set to the WORD corresponding to this number.
     If this line is empty, the selection list is printed again.
     Otherwise, the value of the parameter NAME is set to null.  The
     contents of the line read from standard input is saved in the
     parameter REPLY.  LIST is executed for each selection until a
     break or end-of-file is encountered.

( LIST )
     Execute LIST in a subshell.  Traps set by the trap builtin are
     reset to their default values while executing LIST.

{ LIST }
     Execute LIST.

function WORD ... [ () ] [ TERM ] { LIST }
WORD ... () [ TERM ] { LIST }
WORD ... () [ TERM ] COMMAND
     where TERM is one or more newline or ;.  Define a function which
     is referenced by any one of WORD.  Normally, only one WORD is
     provided; multiple WORDs are usually only useful for setting traps.
     The body of the function is the LIST between the { and }.  See
     Note: Functions.

     If the option SH_GLOB is set for compatibility with other shells,
     then whitespace may appear between between the left and right
     parentheses when there is a single WORD;  otherwise, the
     parentheses will be treated as forming a globbing pattern in that
     case.

time [ PIPELINE ]
     The PIPELINE is executed, and timing statistics are reported on
     the standard error in the form specified by the TIMEFMT parameter.
     If PIPELINE is omitted, print statistics about the shell process
     and its children.

[[ EXP ]]
     Evaluates the conditional expression EXP and return a zero exit
     status if it is true.  See Note: Conditional Expressions for a
     description of EXP.