This is an issue caused with the way bash implements pipes. When piping input to a while, I believe that bash executed the while in a child processes which causes any changes to variables inside of the while to be lost.
This is one reason I prefer kshell over bash. If you have a modern kshell, I suggest you use it. If not then try writing your output to a temp file and reading it into the while.
Try this in both shells to see the difference. Ksh gets the answer right after the loop both times.
Last edited by agama; 11-07-2011 at 12:45 AM..
Reason: typo
Hi...
i am trying to ping my servers .The hostnames are present in a file .They are separated by spaces in the file .
i am doing the following :
a=1
for name in $(cat host2 |cut -d" " -f$a)
do
echo Pinging server $name
ping -c5 $name
a=$a+1
done
It is... (3 Replies)
i have these data in a variable "$test"
BUNGA TERATAI 3 5055 ITH 1 1
JADE TRADER 143W ITH 4 4
MOL SPLENDOR 0307A ITH 3 3
the red coloured are the ones that i want to take and compare
what I need to do is to take out the red coloured and then compare to another variable, if same then... (0 Replies)
Hi,
Is it possible to assign one variable to other.
eg.
v1="table1"
v2="20000"
I want table1 to assign 20000
table1=20000
Is there any way?
Thanks (2 Replies)
Hi
I have webserver that I do read data from.
Data are stored like this:
Huston |1
Portland |2
Hazen |1
Minneapolis |4
Albany |1
Pittsburg |1
Albany |1
Huston |1
Portland|1
Hazen |2
Albany |2
Huston |1
Hazen |1
Script #!/bin/sh
user="admin" (1 Reply)
Hello all,
I find it hard to explain what I need so I will post the code
OVZINCLUDE="16810 16811 1689"
PLUS_16810="test"
PLUS_16811="test"
for VPS in $OVZINCLUDE
do
echo "Dumping VPSes: $OVZINCLUDE "
vzdump --compress --snapshot ${PLUS_$VPS} $VPS
done
... (2 Replies)
Simple enough problem I think, I just can't seem to get it right.
The below doesn't work as intended, it's just a function defined in a much larger script:
CheckValues() {
for field in \
Group_ID \
Group_Title \
Rule_ID \
Rule_Severity \
... (2 Replies)
I have a group of variables myLINEcnt1 - myLINEcnt10. I'm trying to printout the values using a for loop. I am at the head banging stage since i'm sure it has to be a basic syntax issue that i can't figure out.
For myIPgrp in 1 2 3 4 5 6 7 8 9 10; do
here i want to output the value of... (4 Replies)
Hello guys,
This truly is a newbie question. I'm trying to make a loop to execute simultaneous commands indefinitely while using variable. Here is how my mess looks like (this is just an example):
#!/bin/bash
IP=`shuf -n 1 IP.txt` # I figured this would be easier to select random lines... (4 Replies)
Hello All,
Maybe I'm Missing something here but I have NOOO idea what the heck is going on with this....?
I have a Variable that contains a PATTERN of what I'm considering "Illegal Characters". So what I'm doing is looping
through a string containing some of these "Illegal Characters". Now... (5 Replies)
Hi All,
I have a file which has hundred of records with fixed number of fields. In each record there is set of 8 characters which represent the duration of that activity. I want to sum up the duration present in all the records for a report. The problem is the duration changes per record so I... (5 Replies)
Discussion started by: danish0909
5 Replies
LEARN ABOUT REDHAT
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)