Sponsored Content
Full Discussion: While loop
Top Forums Shell Programming and Scripting While loop Post 302932410 by Prani on Wednesday 21st of January 2015 11:30:06 AM
Old 01-21-2015
Thanks for your replies Corona668 and Rudic.

I have verified that Rudic is indeed right and the script will always read the last line of the file as i want it to. I have made some changes and the new script stands at:

Code:
#!/bin/csh
 # demoloop.csh - Sample loop script
 set x = 1
 while ( $x != 4 )
   set x=`tail -1 hist1.dat | awk '{print $2}'`
   sleep 2
   echo $x
 end
echo "done"

This actually does exactly what i ask it to do. Now instead of just outputting "done" at the end, i would like to change the directory and then launch a bunch of commands. This however does not happen.

If i add cd /users/

It doesnt actually go to that directory. Any ideas why this may be happening?

Last edited by rbatte1; 01-21-2015 at 01:09 PM.. Reason: Changed ICODE tags to just CODE tags
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Is there a better way I could have run this loop. (For loop with two variables)

Sorry for such a dreadful title, but I'm not sure how to be more descriptive. I'm hoping some of the more gurutastic out there can take a look at a solution I came up with to a problem, and advice if there are better ways to have gone about it. To make a long story short around 20K pieces of... (2 Replies)
Discussion started by: DeCoTwc
2 Replies

2. Shell Programming and Scripting

Using variables created sequentially in a loop while still inside of the loop [bash]

I'm trying to understand if it's possible to create a set of variables that are numbered based on another variable (using eval) in a loop, and then call on it before the loop ends. As an example I've written a script called question (The fist command is to show what is the contents of the... (2 Replies)
Discussion started by: DeCoTwc
2 Replies

3. Shell Programming and Scripting

Null Handling in Until loop. . .loop won't stop

Hi Im running this script, which is supposed to find the max value build some tables and then stop running once all the tables are built. Thing is , it keeps assigning a null value to $h and then $g is null so it keep building tables i.e. testupdateNUL. How can I stop this? Here is what I have: ... (4 Replies)
Discussion started by: brandono66
4 Replies

4. Shell Programming and Scripting

BASH loop inside a loop question

Hi all Sorry for the basic question, but i am writing a shell script to get around a slightly flaky binary that ships with one of our servers. This particular utility randomly generates the correct information and could work first time or may work on the 12th or 100th attempt etc !.... (4 Replies)
Discussion started by: rethink
4 Replies

5. Shell Programming and Scripting

S# in a for loop - concatenate $(loop counter)

Hi, hope I am posting in the right section. My problem is that I have 2 or more arguments passed and I want to check if the arguments passed exists or not. The first argument should not exist and the remaining others should exist. example: ./shells.sh argument1 argument2 argument3 ... (5 Replies)
Discussion started by: fight4love
5 Replies

6. Shell Programming and Scripting

My for loop decides to become an infinite loop?

Hi, I was debating if I should put this in the dummies or scripts section, I apologize in advance if I chose poorly. Fairly new to Unix and BASH scripting but I thought I made it fairly well given my limited understanding. However, the output indicates that it's looping and I'm ending up with a... (5 Replies)
Discussion started by: gotreef
5 Replies

7. Shell Programming and Scripting

Array Variable being Assigned Values in Loop, But Gone when Loop Completes???

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)
Discussion started by: mrm5102
5 Replies

8. Shell Programming and Scripting

Reset while loop to loop same file multiple times

Hi, I want to read file multiple times. Right now i am using while loop but that is not working. ex. While read line do while read line2 do echo stmt1 #processing some data based on data., done < file2.txt done < file1.txt # This will have 10... (4 Replies)
Discussion started by: tmalik79
4 Replies

9. Shell Programming and Scripting

awk loop using array:wish to store array values from loop for use outside loop

Here's my code: awk -F '' 'NR==FNR { if (/time/ && $5>10) A=$2" "$3":"$4":"($5-01) else if (/time/ && $5<01) A=$2" "$3":"$4-01":"(59-$5) else if (/time/ && $5<=10) A=$2" "$3":"$4":0"($5-01) else if (/close/) { B=0 n1=n2; ... (2 Replies)
Discussion started by: klane
2 Replies

10. Shell Programming and Scripting

For loop or while loop from a text file

Hi all, i developed a script to measure the uptime of a process in a Solaris 10/11 environments. All is well, but i came across a situation where there are multiple processes of the same name. Basically i have the following result file: beVWARS 13357 19592122 beVWARS 14329 19591910... (4 Replies)
Discussion started by: nms
4 Replies
JRUBY(1)							       LOCAL								  JRUBY(1)

NAME
jruby -- Interpreted object-oriented scripting language SYNOPSIS
jruby [--copyright] [--version] [-Sacdlnpswvy] [-0[octal]] [-C directory] [-F pattern] [-I directory] [-K c] [-T[level]] [-e command] [-i[extension]] [-r library] [-x[directory]] [--] [program_file] [argument ...] DESCRIPTION
Jruby is a 100% pure-Java implementation of Ruby, an interpreted scripting language for quick and easy object-oriented programming. It has many features to process text files and to do system management tasks (as in Perl). It is simple, straight-forward, and extensible. OPTIONS
Ruby interpreter accepts following command-line options (switches). They are quite similar to those of perl(1). --copyright Prints the copyright notice. --version Prints the version of Ruby interpreter. -0[octal] (The digit ``zero''.) Specifies the input record separator ($/) as an octal number. If no digit is given, the null character is taken as the separator. Other switches may follow the digits. -00 turns Ruby into paragraph mode. -0777 makes Ruby read whole file at once as a single string since there is no legal character with that value. -C directory Causes Ruby to switch to the directory. -F pattern Specifies input field separator ($;). -I directory Used to tell Ruby where to load the library scripts. Directory path will be added to the load-path variable ($:). -K kcode Specifies KANJI (Japanese) encoding. -S Makes Ruby use the PATH environment variable to search for script, unless if its name begins with a slash. This is used to emulate #! on machines that don't support it, in the following manner: #! /usr/local/bin/ruby # This line makes the next one a comment in Ruby exec /usr/local/bin/ruby -S $0 $* -T[level] Turns on taint checks at the specified level (default 1). -a Turns on auto-split mode when used with -n or -p. In auto-split mode, Ruby executes $F = $_.split at beginning of each loop. -c Causes Ruby to check the syntax of the script and exit without executing. If there are no syntax errors, Ruby will print ``Syntax OK'' to the standard output. -d --debug Turns on debug mode. $DEBUG will be set to true. -e command Specifies script from command-line while telling Ruby not to search the rest of arguments for a script file name. -h --help Prints a summary of the options. -i extension Specifies in-place-edit mode. The extension, if specified, is added to old file name to make a backup copy. For example: % echo matz > /tmp/junk % cat /tmp/junk matz % ruby -p -i.bak -e '$_.upcase!' /tmp/junk % cat /tmp/junk MATZ % cat /tmp/junk.bak matz -l (The lowercase letter ``ell''.) Enables automatic line-ending processing, which means to firstly set $ to the value of $/, and secondly chops every line read using chop!. -n Causes Ruby to assume the following loop around your script, which makes it iterate over file name arguments somewhat like sed -n or awk. while gets ... end -p Acts mostly same as -n switch, but print the value of variable $_ at the each end of the loop. For example: % echo matz | ruby -p -e '$_.tr! "a-z", "A-Z"' MATZ -r library Causes Ruby to load the library using require. It is useful when using -n or -p. -s Enables some switch parsing for switches after script name but before any file name arguments (or before a --). Any switches found there are removed from ARGV and set the corresponding variable in the script. For example: #! /usr/local/bin/ruby -s # prints "true" if invoked with `-xyz' switch. print "true " if $xyz On some systems $0 does not always contain the full pathname, so you need the -S switch to tell Ruby to search for the script if necessary. To handle embedded spaces or such. A better construct than $* would be ${1+"$@"}, but it does not work if the script is being interpreted by csh(1). -v --verbose Enables verbose mode. Ruby will print its version at the beginning, and set the variable $VERBOSE to true. Some methods print extra messages if this variable is true. If this switch is given, and no other switches are present, Ruby quits after printing its version. -w Enables verbose mode without printing version message at the beginning. It sets the $VERBOSE variable to true. -x[directory] Tells Ruby that the script is embedded in a message. Leading garbage will be discarded until the first that starts with ``#!'' and contains the string, ``ruby''. Any meaningful switches on that line will applied. The end of script must be spec- ified with either EOF, ^D (control-D), ^Z (control-Z), or reserved word __END__. If the directory name is specified, Ruby will switch to that directory before executing script. -y --yydebug Turns on compiler debug mode. Ruby will print a bunch of internal state messages during compiling scripts. You don't have to specify this switch, unless you are going to debug the Ruby interpreter. UNIX
Apr 2, 2007 UNIX
All times are GMT -4. The time now is 09:33 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy