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Top Forums Shell Programming and Scripting String concatenation not working in a loop Post 302389811 by LostInTheWoods on Tuesday 26th of January 2010 02:34:56 AM
Old 01-26-2010
String concatenation not working in a loop

Hi,

First post, so I hope someone can help me with this weirdness Smilie

I have a number files with some rows of information I want to extract, at the same time I want to add to a string some details from the file. I have found two different ways of looping over rows in a file, but one method doesn't let me concatenarte strings and I don't know why....

The first method sets the IFS environmental variable. I don't really favour this method, but it works..

Code:
#!/bin/bash -
OLDIFS=$IFS
IFS='
'

STE="cat"
  
for FILE in $( ls *-df | cut -f 4 -d / ); do
  N=0
  for LINE in $( cat $FILE ); do
    N=$((N+1))
    STE="$STE""dog"
  done
done
echo "$STE" && exit

and produces:
catdogdogdogdogdogdogdogdogdogdogdogdogdogdogdogdo gdogdogdogdogdogdogdogdogdogdogdogdog


Method 2 uses "read" but prevents the concatenation of the string:
Code:
#!/bin/bash -
STE="cat"
  
for FILE in $( ls *-df | cut -f 4 -d / ); do
  N=0
  cat "$FILE" | while read LINE ; do
    N=$((N+1))
    STE="$STE""dog"
  done
done
echo "$STE" && exit

and produces:
cat

Why is there a difference in the two methods? I would rather not be changing environmental variables and a simple loop is my preferred choice.

Thanks for your help, as this has been driving me crazy...
Stephen
 

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gnomevfs-cat(1) 						   User Commands						   gnomevfs-cat(1)

NAME
gnomevfs-cat - print a file to standard output using the VFS system SYNOPSIS
gnomevfs-cat URI DESCRIPTION
gnomevfs-cat is obsolete. It has been superseded by gvfs-cat. See gvfs-cat(1). gnomevfs-cat prints a file to standard output using the virtual file system to access the file via a URI. OPERANDS
The following operands are supported: URI Specifies the file location in standard URI format. EXAMPLES
Example 1: Cat a File From a Web Server example% gnomevfs-cat http://www.sun.com Example 2: Cat a Local File example% gnomevfs-cat file:///home/user/README.txt ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables: NLSPATH. EXIT STATUS
The exit value 0 is returned regardless of success or failure. FILES
The following files are used by this application: /usr/bin/gnomevfs-cat Executable to print a file to standard output using the VFS system ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWgnome-vfs | +-----------------------------+-----------------------------+ |Interface stability |Obsolete Volatile | +-----------------------------+-----------------------------+ SEE ALSO
gnomevfs-copy(1), gnomevfs-info(1), gnomevfs-ls(1), gnomevfs-mkdir(1), gvfs-cat(1), attributes(5), environ(5) NOTES
Written by Stephen Browne, Sun Microsystems Inc., 2004. SunOS 5.11 14 May 2008 gnomevfs-cat(1)
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