Setting a variable in a while loop (.ksh script)

jimmy75_13 · July 8, 2011, 3:58am

Hello Everyone,

I'm still trying to grasp many concepts in .ksh scripting, one of them being variables inside loops. My problem is the following:

I'm trying to set a variable inside a while read loop to reuse it outside of said loop. My lines are the following :

file="/home/jpassema/purge_/appli"

IFS="&"
cat $file | while read UPROC REP_CIBLE LIST_REP_SOURCE
do
        if [ "$UPROC" = "$uproc_cible" ]; then
                (( rep_cible=$REP_CIBLE ))
                (( liste_rep_sources=$LIST_REP_SOURCE ))
        fi
done

echo "repertoire cible = $rep_cible"

basically i'm trying to read a file until i find the line designated by the value "uproc_cible" and setting the contents of the colums on that line to script-wide variables.

I believe that loops run as parrallel processes, which may be the source of my problem.

Thanks in advance for any pointers

Jimmy

funksen · July 8, 2011, 4:24am

IFS="&" ; grep "^${uproc_cible}" yourfile | read  uproc rep_cible liste_rep_sources

this should work, but it's untested

jimmy75_13 · July 8, 2011, 4:36am

Hi Funksen,

Thanks for your prompt reply.
As i undestand it, this command will find the line identified by "uproc_cible" and set the variables : uproc, rep_cible, liste_rep_sources with the values in that line.

stop me if i'm wrong....

---------- Post updated at 10:36 AM ---------- Previous update was at 10:30 AM ----------

Here is the modification I made following your recommendation :

IFS="&" ; grep "${uproc_cible}" $file | read  uproc rep_cible liste_rep_sources

echo $uproc
echo $rep_cible

and this is the output:

+ file=/home/jpassema/purge_/appli
+ IFS=&
+ grep uproc1 /home/jpassema/purge_/appli
+ read uproc rep_cible liste_rep_sources
+ echo

+ echo

perhaps i goofed up the syntax??

itkamaraj · July 8, 2011, 5:25am

Try this..

 
file="/home/jpassema/purge_/appli"
rep_cible=""
IFS="&"
cat $file | while read UPROC REP_CIBLE LIST_REP_SOURCE
do
if [ "$UPROC" = "$uproc_cible" ]; then
(( rep_cible=$REP_CIBLE ))
(( liste_rep_sources=$LIST_REP_SOURCE ))
fi
done
echo "repertoire cible = $rep_cible"

funksen · July 8, 2011, 5:28am

hm looks good, but since you want to find the content of uproc_cible in the first column, you'll need the

in the grep, this indicates the beginning of the line

but this has nothing to do with your problem, since the variables should contain anything

the read syntax will not work in sh or bash, just in ksh

maybe give a short example of the content of uproc_cible and the file

possible issue could be, that the search string cannot be found in the file, case problem perhaps? use grep -i to ignore case

jimmy75_13 · July 8, 2011, 5:29am

Hi Itkamaraj,

I have tried your solution, here is the output:

file=/home/jpassema/purge_/appli
+ rep_cible=
+ IFS=&
+ cat /home/jpassema/purge_/appli
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc1 = uproc1 ]
+ let  rep_cible=uproc1_rep_source
+ let  liste_rep_sources=rep_source1|rep_source2|rep_source3
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc2 = uproc1 ]
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo repertoire cible =
repertoire cible =

itkamaraj · July 8, 2011, 5:32am

 
file="/home/jpassema/purge_/appli"
rep_cible=""
IFS="&"
cat $file | while read UPROC REP_CIBLE LIST_REP_SOURCE
do
if [ "$UPROC" = "$uproc_cible" ]; then
echo $REP_CIBLE   # to check the value
rep_cible=$REP_CIBLE
liste_rep_sources=$LIST_REP_SOURCE
fi
done

echo "repertoire cible = $rep_cible"

jimmy75_13 · July 8, 2011, 5:38am

Funksen,

My goal is not the content of Uproc but the content on the same line. Uproc is an identifier (unique of course).

This is the test content of the file to be read :

uproc1&uproc1_rep_source&rep_source1|rep_source2|rep_source3
uproc2&uproc2_rep_source&rep_source1|rep_source2|rep_source3

---------- Post updated at 11:36 AM ---------- Previous update was at 11:33 AM ----------

@Itkamaraj :

Here is the output (null value):

+ file=/home/jpassema/purge_/appli
+ rep_cible=
+ IFS=&
+ cat /home/jpassema/purge_/appli
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc1 = uproc1 ]
+ echo repertoire cible =
repertoire cible =
+ let  rep_cible=uproc1_rep_source
+ let  liste_rep_sources=rep_source1|rep_source2|rep_source3
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc2 = uproc1 ]
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo repertoire cible =
repertoire cible =

---------- Post updated at 11:38 AM ---------- Previous update was at 11:36 AM ----------

However when i try to insert an echo at the end of the "if" statement, here is the output:

+ file=/home/jpassema/purge_/appli
+ rep_cible=
+ IFS=&
+ cat /home/jpassema/purge_/appli
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc1 = uproc1 ]
+ echo repertoire cible =
repertoire cible =
+ let  rep_cible=uproc1_rep_source
+ let  liste_rep_sources=rep_source1|rep_source2|rep_source3
+ echo repertoire cible = 0
repertoire cible = 0
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ [ uproc2 = uproc1 ]
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo repertoire cible =
repertoire cible =

"repertoire cible" should contain a string, not an integer

itkamaraj · July 8, 2011, 6:03am

then the problem is reading from the file.

what is your file contents ? ( post some lines )

wherever you compare the values ( do some echo for testing and make sure it gets and got the correct data )

also echo this value $uproc_cible

jimmy75_13 · July 8, 2011, 8:28am

I have added echos to test the values of uproc_cible (the script input), and UPROC, the line read. Those echos echo the proper values (output below)

+ uproc_cible=uproc1
+ [ ! -f /home/jpassema/purge_/appli ]
+ [ ! -f /home/jpassema/purge_/uproc ]
+ file=/home/jpassema/purge_/appli
+ echo uproc1
uproc1
+ rep_cible=
+ IFS=&
+ cat /home/jpassema/purge_/appli
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo premiere ligne = uproc1
premiere ligne = uproc1
+ [ uproc1 = uproc1 ]
+ echo repertoire cible =
repertoire cible =
+ let  rep_cible=uproc1_rep_source
+ let  liste_rep_sources=rep_source1|rep_source2|rep_source3
+ echo repertoire cible = 0
repertoire cible = 0
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo premiere ligne = uproc2
premiere ligne = uproc2
+ [ uproc2 = uproc1 ]
+ read UPROC REP_CIBLE LIST_REP_SOURCE
+ echo repertoire cible =
repertoire cible =

---------- Post updated at 02:28 PM ---------- Previous update was at 02:18 PM ----------

and here is the format of my conf file :

uproc1&uproc1_rep_source&rep_source1|rep_source2|rep_source3

the 3 columns are

1: uproc1 2: uproc1_rep_source
3: rep_source1|rep_source2|rep_source3

kshji · July 8, 2011, 2:34pm

Using pipe read and set variable globally works only in ksh and zsh.

grep "^$uproc_cible&" $file | IFS="&" read  uproc rep_cible liste_rep_sources
echo "uproc:$uproc"
echo "rep_cible:$rep_cible"

Generic sh version, works in all about posix sh like ksh, dash, bash, ...

IFS="&" read  uproc rep_cible liste_rep_sources <<EOF
$(grep "^$uproc_cible&" $file )
EOF
echo "uproc:$uproc"
echo "rep_cible:$rep_cible"

jimmy75_13 · July 11, 2011, 3:20am

Hi kshji,

Thanks for the suggestion. It still doesn't work, which tells me that the issue is probably the file in itself or something of that sort.Could it come from the format of the file or perhaps from my bash version : "GNU bash, version 3.2.25(1)-release (x86_64-redhat-linux-gnu)"

Franklin52 · July 11, 2011, 5:41am

Try this:

file="/home/jpassema/purge_/appli"

while IFS="&" read UPROC REP_CIBLE LIST_REP_SOURCE
do
  if [ "$UPROC" = "$uproc_cible" ]; then
    rep_cible=$REP_CIBLE
    liste_rep_sources=$LIST_REP_SOURCE
  fi
done < $file

echo "repertoire cible = $rep_cible"

jimmy75_13 · July 11, 2011, 5:59am

Thanks a lot Franklin52,

It seems i was not able to properly read the file. Your code works just fine.
Thanks again!!