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


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting S# in a for loop - concatenate $(loop counter)
# 1  
Old 07-05-2011
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

Code:
#!/bin/bash
if [ $# -eq 1 ]
then 
	echo "There should be two or more filenames."
	exit 1
fi
if [ -f $1 ]
then
	echo "Sorry, $1 file should not exist"
else
	num=$#
	echo "number of files is: $num"	
	for var in `seq 2 $num`
	do	
		if [ -f $`$var` ]
		then
			echo "$var exists"
		fi
	done	
fi

how do I change this line
Code:
if [ -f $`$var` ]

so that it would become
Code:
if [ -f $2 ]

or
Code:
 if [ -f $3 ]

and so on..

I tried many variations but I always get error like substitution error or command not found.

I would really appreciate your replies. Thanks!

Last edited by fight4love; 07-05-2011 at 11:38 PM..
# 2  
Old 07-06-2011
Not quite sure that I understand your reasoning, nevertheless, here it goes; a shut in the dark:
Code:
else
	shift
	
	for arg in $@
	do	
		if [ -f "$arg" ]
		then
			echo "$arg exists"
		fi
	done	
fi

This User Gave Thanks to Aia For This Post:
# 3  
Old 07-06-2011
thanks!

I'll try this.
# 4  
Old 07-06-2011
thank you so much! this works! Smilie
# 5  
Old 07-06-2011
Quote:
Originally Posted by Aia
Code:
else
	shift
	
	for arg in $@
	do	
		if [ -f "$arg" ]
		then
			echo "$arg exists"
		fi
	done	
fi

I'd make one small change to Aia's suggestion:

Code:
for arg in "$@"

Quoting $@ preserves any whitespace that might have been a part of the parameter on the command line. Unfortunately people do create filenames which have spaces, and if the command line were something like this

Code:
script-name nosuchfile "my big file"

using $@ without the quotes would cause the loop to execute and test "my" "big" and "file" as three separate names, rather than the single name entered on the command line.

Filenames with spaces are a personal pet peeve, and your environment might not have any for you to worry about, but from a more generic command line processing perspective, knowing the difference between $@ and "$@" might make a difference as you write scripts in future.
This User Gave Thanks to agama For This Post:
# 6  
Old 07-06-2011
thanks for adding! I really appreciate it. Thank you also for sharing the difference of $@ with and without double quotes. Thanks!
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

While loop with limit counter

#!/usr/bin/ksh c=0 while ]; do echo /tmp/unex NOT found, iter : $c; ((c = $c + 1)); sleep 2; done so, the above counter doesn't work, already tried both -lt & -gt, and changed || to && so what am I missing? Thanks in advance (5 Replies)
Discussion started by: unexistance
5 Replies

2. Shell Programming and Scripting

Loop counter resets by itself

Hi! Can anyone explain this? The counter CDR_count should go on forever, but it suddenly resets at every step of the FOR loop (I know this because $_file has exactly 378 records). However, the counter reset is OUTSIDE the FOR loop. What's going on?? #!/bin/bash if || ; then echo ... (8 Replies)
Discussion started by: Flavius
8 Replies

3. Shell Programming and Scripting

Avoid multiple emails being sent - Counter, Loop?

Hello, I have currently coded a bash script below in which it does the following: # Archives compressed file from another location. Basically it moves *.gz files to another location. The script also sends an email whenever a new compressed file is placed. This is the issue that i... (5 Replies)
Discussion started by: Wizard_1979
5 Replies

4. Shell Programming and Scripting

Loop usage with counter

Hi friends, I just want to try some thing with shell using loop and counter I have 30 Directory, in each directory number of files say 5, 10, 20 etc... directory_1 directory_2 directory_n what I want to do is read files from directory_1 say 5 files if my counter is like this m=2000 ... (6 Replies)
Discussion started by: Akshay Hegde
6 Replies

5. Shell Programming and Scripting

How to implement the counter in loop?

Hi, I am working on a script where I need to add one functionality i.e. to could the number of tar files at particular location...but the script is working in below way. 1) create sandbox 2) Drop old member function 3) addmember function 4) Apply checkpoint lable 5) Resync operation(This... (1 Reply)
Discussion started by: anuragpgtgerman
1 Replies

6. Shell Programming and Scripting

File merging based on different counter loop

hello, File 1 main Group sub group MIT VAR_1D_DATA_TYPE 23-03-2012 MIT VAR_1D_DATA_TYPE 22-03-2012 MIT VAR_10D_DATA_TYPE 23-03-2012 MIT VAR_10D_DATA_TYPE 22-03-2012 MIT ... (0 Replies)
Discussion started by: manas_ranjan
0 Replies

7. Shell Programming and Scripting

loop with a counter on a constant in bash

Hello Everyone, I'm in need of assistance on creating a script with a counter on a certain string. Basically this script opens a log file and displays certain log data. There are two key words in the log. START and FINISH. In between the START and FINISH is a variable ACTNUMBER. It will... (1 Reply)
Discussion started by: rxc23816
1 Replies

8. Shell Programming and Scripting

adding counter to a variable while moving in a loop

The scenario is like this : I need to read records from a file one by one and increment counter1, if a certain field matches with a number say "40"..the script should increment the counter2 and also extract a corresponding field from the same line and adding them one by one and redirecting the the... (5 Replies)
Discussion started by: mady135
5 Replies

9. Shell Programming and Scripting

Using the counter of a for loop in command line parameter

Say I have (in psuedocode) For i=1 to 10 tar cvfb /... 5*i /junk(i) end What I mean is that I want each successive for loop to have the block size parameter be 5 times the current counter. This isn't my actual code, just a stupid example...So the question is how do I descrive that parameter... (2 Replies)
Discussion started by: jeriryan87
2 Replies

10. Shell Programming and Scripting

Loop counter variable display

Hello everyone, how can I send output to the screen from a running script or tcl, in such a way that if a loop is executing I will see the rolling counter on my screen as the records are processed in the loop. I do not want the screen to scroll, though. In other words can a var's value be painted... (2 Replies)
Discussion started by: lifespan
2 Replies
Login or Register to Ask a Question