How to check if a file exists in unix script

Slightly similar to other answers but does not fork cat and entries can contain spaces. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How to test if string exists in file with Bash?

Ask Question. Asked 10 years, 11 months ago. Active 1 year, 1 month ago. Viewed k times. Toren Toren 5, 11 11 gold badges 38 38 silver badges 56 56 bronze badges. To find all of the strings inside a file, you can run grep in FOR loop: unix. Add a comment. Active Oldest Votes. Error handling As rightfully pointed out in the comments, the above approach silently treats error cases as if the string was found. If you want to handle errors in a different way, you'll have to omit the -q option, and detect errors based on the exit status: Normally, the exit status is 0 if selected lines are found and 1 otherwise.

Community Bot 1 1 1 silver badge. Thomas Thomas k 43 43 gold badges silver badges bronze badges. If I execute this command from bash script how to catch 0 or 1 into a variable?

Toren: Without -F , your filename would be interpreted as a regular expression, not as a normal string.

Thus, if it contains strange characters like. The -x flag ensures that the string matches an entire line, not just a part of it: so if you search for foo , only lines containing exactly foo are matched, not foobar.

There was an error in my examples; it still used some regex syntax. Fixed now. A couple of notes for folks looking at this answer: 1 In bash, 0 is always true and anything else is always false 2 Only use the -x flag if you want the entire line to match exactly. If you just want to find if your string exists in the file at all, leave that off. If you want to find if your string exists exactly but without matching an entire line necessarily i.

Last edited by vgersh99; at AM.. Reason: code tags, please. Join Date: Feb Shell script which will check the target file and folder exists and copy it. Hi All, I am a beginner in this and trying to write a shell script in linux which will : 1. Ask for a file name and check if its exists.

If file exists only then it will ask for the new target folder, after entering target folder name it will check if it exists. If target folder Except script fails to check file exists or not in remote node. However the result is always found even if the file exist or doesn't exist.

Check if file exists or not. Hi, I want to check if the file exists or not in the directory. File exists, but cannot be opened. How to check- whether it could be opened to read when it exists.

If it exists, it truncates the database I want to write a script to see if various files exist. I don't actually know of how to check and see if a file exists or not.

What I have in mind Script to check file exists. Script to check for the file existence, if file exists it should echo the no of modified days. Hi, I am looking for a shell script with the following. It should check whether a particular file exists in a location! If file exists, it should check for the modified date and run a command Shell script to check if any file exists in 4 folders.

In Java , we can delete a file by using the File. The delete method deletes the file or directory denoted by the abstract pathname. If the pathname is a directory, that directory must be empty to delete. Note : This method does not return any value. The following example shows the usage of java. FileWriter: FileWriter is the simplest way to write a file in Java.

It provides overloaded write method to write int, byte array, and String to the File. You can also write part of the String or byte array using FileWriter.

FileWriter writes directly into Files and should be used only when the number of writes is less. To rename a file, we invoke the method renameTo on two objects of type File that represent respectively the file to rename , and the new name to give to the file. The file oldname. Use the String. Java creating file with File The File's createNewFile method creates a new, empty file named by the pathname if a file with this name does not yet exist.

The createNewFile returns true if the named file does not exist and was successfully created; false if the named file already exists. Another approach I can think of is to use lsof grep filename. You can't easily tell if it's in the process of being written to, but if it is being written to, it MUST be open.

Java FileWriter and FileReader classes are used to write and read data from text files they are Character Stream classes. Throwing an exception is as simple as using the " throw " statement. You then specify the Exception object you wish to throw. Every Exception includes a message which is a human-readable error description.

It can often be related to problems with user input, server, backend, etc. It specifies the path of the file or directory you want to check. Return Value: It returns True on success and False on failure. Letting users decide what files to process is more flexible and more consistent with built-in Unix commands.

Using the Find Command. To find files that match a specific pattern, use the -name argument. If find doesn't locate any files matching your criteria, it produces no output.