nixCraft

raj · #1 (**permalink**) 16-11-2008, 09:22 PM

You can easily test if a file exists under Linux operating system using test command.

Display a message if file /etc/passwd exists:

Code:

test -f /etc/passwd && echo 'File exists'

Display a message if file /etc/passwd2 does not exists:

Code:

test -f /etc/passwd2 && echo 'File exists' || echo 'File not found'

You can also use [ ]:

Code:

[ -f /path/file.txt ] && echo 'File exists' || echo 'File not found'

Here is if command example:

Code:

if [ -f /etc/passwd ]
then
     echo 'Adding user to database...'
else
     echo 'File not found!'
fi

More info:

* Find out if file exists with conditional expressions

* man test

thePITman · #2 (**permalink**) 18-11-2008, 09:38 PM

Urgent!

I am having an issue with this. We are switching from UNIX to Linux, so I am going through programs making sure they work on Linux. I am having the following problem:

I run a .prog file that, in turn, runs a PL/SQL program that creates one or more output files that all begin with the same 7 characters, and have similar to the following format:

411n9n_xxx_xxx_timestamp

Once back in the .prog file, my code is as follows:
(I have already changed single brackets to double bracket because of syntax error)

Code:

if [[ -f ${EXPORTDIR}/411n9n* ]]
then
   xxx
fi

This does not work, and the IF statement is not entered into even when there are files located in the folder that meet the requirements. However, if I change the expression to an exact filename (without the * wildcard) it works fine. Is there some kind of limitation on the wildcard in this situation?

Thank you!

thePITman · #3 (**permalink**) 18-11-2008, 10:52 PM

Arrgggh!!! It works now!

The whole problem was the double brackets. However, when it was just single brackets when I first started testing, it gave me an error about "too many" or "not enough arguments" but the error went away when I made it double brackets instead of just one. So the whole time there was nothing wrong with my original code!

What a waste of time. Haha!

nbdwt73 · #4 (**permalink**) 26-11-2008, 06:48 PM

I have a similar issue - We have a Windows based database that is backed up to a linux server (Debian). The file names are similar but with a date suffix. What I need to do is confirm that a particular backup file - or set of files - is present (meaning backup completed) and then process. Script follows:

#!/bin/bash
FILE="/media/Backup/SYS_0*"
if [ -f $FILE ]; then
rm -f /media/Backup/SYS_3*
rename -f 's/SYS_2/SYS_3/' /media/Backup/SYS*
rename -f 's/SYS_1/SYS_2/' /media/Backup/SYS*
rename -f 's/SYS_0/SYS_1/' /media/Backup/SYS*
fi

The problem is that multiple SYS_0... files can exist. The script works fine if only one exists. What am I doing wrong? I have tried thePITman suggestion above but it does not work for me - if [[ -f $FILE ]]...

Thanks for any help.

nbdwt73 · #5 (**permalink**) 27-11-2008, 04:27 PM

Got it... The instruction that works for me is:

if [ ! -f "$FILE" ]; then ...

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