Checking if a file exists


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Checking if a file exists
# 1  
Old 07-23-2008
Checking if a file exists

How can I check if a file exists in shell script. Basically, I want to check if a file Test_msgs has been created today. If it has been then append data to it. Otherwise, create it. I have written the following but it does not work.

todaysdate=$(date +%d%m%Y)
timenow=$(date +%H%M%S)
checktestfile='Test_msgs_$todaysdate_*.txt'
testfile='Test_msgs_'$todaysdate'_'$timenow'.txt'

if [ -f checkTestfile ]; then
echo "File appended to" >> testfile
else
echo "File created" > testfile
fi
# 2  
Old 07-23-2008
Just a silly error; you forgot a "$" before "checkTestfile" inside the -f test. You also mis-capitalized "checkTestfile"; it should be "checktestfile" to match the variable declaration above it.
# 3  
Old 07-23-2008
Hammer & Screwdriver There are a few good tests for file operators

You used the -f, but there are a couple of others also that may be of interest.

if [ -r $checktestfile ] ==> to see if you can read it (may not have access)
if [ -s $checktestfile ] ==> to see if the file is non-zero or not empty

Also, in your scripting, you set a variable
Code:
testfile='Test_msgs_'$todaysdate'_'$timenow'.txt'

But you access it as in -- need the $ before variable
Code:
echo "File created" > $testfile

# 4  
Old 07-23-2008
@gugs:

there is no need for an if condition. You may directly use >> as it will append if file exists, or will create file if it does not exist.

Code:
echo "some text" >> testfile

# 5  
Old 07-23-2008
Quote:
Originally Posted by krishmaths
@gugs:

there is no need for an if condition. You may directly use >> as it will append if file exists, or will create file if it does not exist.

Code:
echo "some text" >> testfile

True, but he wanted the first message in the file to be different based on whether it was created or appended-to. That then requires a test.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

For loop without checking file exists

In several scripts that process files matched by name pattern I needed to add a check for file existence. Just to illustrate let's say I need to process all N??? files: /tmp$ touch N100 N101 /tmp$ l ?10 -rw-rw-r-- 1 moss group 0 Apr 19 11:22 N100 -rw-rw-r-- 1 moss group ... (10 Replies)
Discussion started by: migurus
10 Replies

2. Shell Programming and Scripting

Problem with ssh and checking if file exists

Hi All, I am facing a problem while checking for existence of file over ssh ! Basically, i want to ssh and check if file exists.. If file exists return 1. If file does not exits return 0 (or any value) I am using the below code file_avail=`ssh username@host "if ]; then exit 1;... (10 Replies)
Discussion started by: galaxy_rocky
10 Replies

3. Shell Programming and Scripting

Checking if file exists and unzipping

Hey, I am new to scripting and was wondering what is wrong with this if statement. I want to check if file exists and the if it does to unzip it. I program it as follows if ; then gunzip *_filename.gz fi Thanks in advance! Please use code tags next time for your code and data. (10 Replies)
Discussion started by: mostarac2487
10 Replies

4. Shell Programming and Scripting

Checking whether the file exists under a directory and doing a diff

Hi Everyone, I am writing a shell script for the below needs and would like your suggestions and advices. I have a lot of scripting files(Shell Scripts) under the directory: /home/risk_dev/dev I have another directory which has a lot of shell scripts under the directory: ... (2 Replies)
Discussion started by: filter
2 Replies

5. Shell Programming and Scripting

what is the difference between -f and -e, when checking for file exists

Hi All, what is the difference between -f and -e. Regards, ch33ry (1 Reply)
Discussion started by: ch33ry
1 Replies

6. Shell Programming and Scripting

Checking if file exists

How can I check if a file exists in csh? I know there is "-e $file" but do not know exactly how to use it. I have tried the below but I'm getting "Bad : modifier in $ ( )." foreach f ($AfullnameLst) if (-e $f) then echo "$f: file exists" endif end (6 Replies)
Discussion started by: kristinu
6 Replies

7. Shell Programming and Scripting

Checking if file exists using a NOT operator and shell variable

Hi, I'm new to UNIX, at least shell programming and am having trouble figuring out a problem i'm having. In one section in my nested if statement, i want the program to test if the file does not exist, based on an argument supplied at the command line by the user. What i have is elif ; then... (3 Replies)
Discussion started by: rowlf
3 Replies

8. Shell Programming and Scripting

checking textfile exists or not in all directories

Hai All, please help me in solving this assignment!!! i need a unix script that has to check the text file exists or not in all directories and sub directories if textfile exists display the directory path else display does not exists!! example: kamal.txt that i want to search if the... (5 Replies)
Discussion started by: G.K.K
5 Replies

9. Shell Programming and Scripting

Checking the file if it exists

Hi This will be useful who is looking for checking the files in a directory #chmod 777 /cronacle/tools/teradata/opo/bin/file_check.sh SUBJECT=`echo "File Not Found"` SUBJECT1=`echo "File Found"` #RECIPIENT=Madhu.Reddy@ge.com cd /cronacle/tools/teradata/opo/bin file_list=attach.sh if ... (3 Replies)
Discussion started by: ksmbabu
3 Replies

10. IP Networking

checking a connection still exists?

Hi I have a bit of c code which I'm trying to use as a relay between apache and a scgi cluster. Example of problem code is below: while((n = recv(scgiSock, local_data, MAX_LENGTH, 0)) > 0) { time(&t2); time_now = t2 - t1; if(time_now > TIMEOUT) ... (2 Replies)
Discussion started by: fishman2001
2 Replies
Login or Register to Ask a Question