tcsh: how to prevent a foreach from terminating a script when the result is null?
Sorry if this has been answered. I did search both Google and this site and did find this post: unix.com/unix-dummies-questions-answers/152992-how-ignore-errors-script.html
However, it wasn't answered.
I have the same question - how do you prevent a tcsh script from terminating when the result of a foreach is null?
So if my script does something like:
If the first foreach doesn't match anything, the entire script terminates with the error:
foreach: No match.
How do you prevent this? Do you have to do a check for the presence of anything you need to do a foreach on?
Hi,
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Hi everyone,
I am new to the linux.I wrote a small script and assigning two values to fname and lname and I want if the fname or lname are not given proper name like Toys or Gun the script should terminate and if they are given proper name it should execute.please help thanks:wall:
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Dear all,
For example, if data contains following numbers:1 2 3 4 5 6
I would like get like below using foreach command,1 2
1 3
1 4
1 5
1 6
2 3
2 4
2 5
2 6
3 4
3 5
3 6
4 5 (1 Reply)
Discussion started by: Ryan Kim
1 Replies
LEARN ABOUT OPENDARWIN
foreach
foreach(n) Tcl Built-In Commands foreach(n)
__________________________________________________________________________________________________________________________________________________NAME
foreach - Iterate over all elements in one or more lists
SYNOPSIS
foreach varname list body
foreach varlist1 list1 ?varlist2 list2 ...? body
_________________________________________________________________DESCRIPTION
The foreach command implements a loop where the loop variable(s) take on values from one or more lists. In the simplest case there is one
loop variable, varname, and one list, list, that is a list of values to assign to varname. The body argument is a Tcl script. For each
element of list (in order from first to last), foreach assigns the contents of the element to varname as if the lindex command had been
used to extract the element, then calls the Tcl interpreter to execute body.
In the general case there can be more than one value list (e.g., list1 and list2), and each value list can be associated with a list of
loop variables (e.g., varlist1 and varlist2). During each iteration of the loop the variables of each varlist are assigned consecutive
values from the corresponding list. Values in each list are used in order from first to last, and each value is used exactly once. The
total number of loop iterations is large enough to use up all the values from all the value lists. If a value list does not contain enough
elements for each of its loop variables in each iteration, empty values are used for the missing elements.
The break and continue statements may be invoked inside body, with the same effect as in the for command. Foreach returns an empty string.
EXAMPLES
The following loop uses i and j as loop variables to iterate over pairs of elements of a single list. set x {} foreach {i j} {a b c d e f}
{
lappend x $j $i } # The value of x is "b a d c f e" # There are 3 iterations of the loop.
The next loop uses i and j to iterate over two lists in parallel. set x {} foreach i {a b c} j {d e f g} {
lappend x $i $j } # The value of x is "a d b e c f {} g" # There are 4 iterations of the loop.
The two forms are combined in the following example. set x {} foreach i {a b c} {j k} {d e f g} {
lappend x $i $j $k } # The value of x is "a d e b f g c {} {}" # There are 3 iterations of the loop.
SEE ALSO
for(n), while(n), break(n), continue(n)
KEYWORDS
foreach, iteration, list, looping
Tcl foreach(n)