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Full Discussion: for loop iteration and shell programming startup
Top Forums Shell Programming and Scripting for loop iteration and shell programming startup Post 302589982 by methyl on Friday 13th of January 2012 09:33:04 AM
Old 01-13-2012
Java
Quote:
question :how can i iterate to next item in for loop with the loop
e.g

for i in `cat abc.txt`
do
echo $i // this will display first line
i=$i+1; // this doesnt work for me.
echo $i; //this will display secound line
done
If we are working with lines, we do not want to expand the entire file "abc.txt" on the "for" line and then read it word by word.
We need to read each line one-by one with a method which preserves the record construct.
Code:
cat abc.txt | while read line
do
          echo "${line}"          # Display line
done

To make the extra read in the while loop:
Code:
cat abc.txt | while read line
do
          echo "${line}"          # Display first line and every odd-numbered line
          read line                  # Read even numbered lines
          echo "${line}"           # Display 2nd line and every even-numbered line
done


Don't understand your second question. Not clear which file is which or what the process is.
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LEARN ABOUT OSF1

line

line(1) 						      General Commands Manual							   line(1)

NAME

       line - Reads one line from standard input

SYNOPSIS

       line

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       line:  XCU5.0

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

OPTIONS

       None

DESCRIPTION

       The  line  command  copies one line, up to and including a newline, from standard input and writes it to standard output.  Use this command
       within a shell command file to read from your terminal.	The line command always writes at least a newline character.

NOTES

       The line utility has no internationalization features and is marked LEGACY in XCU Issue 5. Use the read utility instead.

EXIT STATUS

       Success.  End-of-File.

EXAMPLES

       To read a line from the keyboard and append it to a file, enter: echo 'Enter comments for the log:' echo ': c' line >>log

       This shell procedure displays the message: Enter comments for the log:

       It then reads a line of text from the keyboard and adds it to the end of the file log.  The echo  ':  c'  command  displays  a	:  (colon)
       prompt.	See the echo command for information about the c escape sequence.

SEE ALSO

       Commands:  echo(1), ksh(1), read(1), Bourne shell sh(1b), POSIX shell sh(1p)

       Functions:  read(2)

       Standards:  standards(5)

																	   line(1)
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