How do I check if a file is not empty in Unix?

touch /tmp/f1 echo “data” >/tmp/f2 ls -l /tmp/f{1,2} [ -s /tmp/f1 ] echo $? The non zero output indicate that file is empty. [ -s /tmp/f2 ] echo $? The zero output indicate that file is not empty.

How can I check if a file is empty?

Check empty file?

1. package com. app;
2. io. File;
3. public class CheckEmptyFile {
4. if (file. length() == 0)
5. System. out. println(“File is empty!!!”);
6. else.
7. System. out. println(“File is not empty!!!”);
8. }

9 янв. 2017 г.

How find non empty files in Linux?

Find all (non-)empty files in a directory

Ditto for non-empty files. By default, the find command excludes symbolic files. Use the -L option to include them. The expression -maxdepth 1 specifies that the maximum depth to which the search will drill is one only.

How do you check if a file is still being written in Unix?

You can use lsof | grep /absolute/path/to/file. txt to see if a file is open. If the file is open, this command will return status 0, otherwise it will return 256 (1).

How do I check if grep is nothing?

Another simple way is to use grep -c . That outputs (not return as exit code), the number of lines that match the pattern, so 0 if there’s no match or 1 or more if there’s a match. So, if you wanted to check that the pattern is matched 3 or more times, you would do: if [ “$(grep -c “^$1” schemas.

How do I check if a file is empty in Shell?

Check If File Is Empty Or Not Using Shell Script

1. touch /tmp/file1 ls -l /tmp/file1 find /tmp -empty -name file1.
2. echo “data” > /tmp/file2 ls -l /tmp/file2 find /tmp -empty -name file2.
3. touch /tmp/f1 echo “data” >/tmp/f2 ls -l /tmp/f{1,2} [ -s /tmp/f1 ] echo $?
4. [ -s /tmp/f2 ] echo $?
5. #!/bin/bash _file=”$1″ [ $# -eq 0 ] && { echo “Usage: $0 filename”; exit 1; } [ ! –

12 дек. 2018 г.

How do I check if a Jsonobject is empty?

return Object.keys(obj).length === 0;

We can also check this using Object. values and Object. entries . This is typically the easiest way to determine if an object is empty.

Is file empty Java?

The common approach for checking if a file is empty or not is to first check if the file exists or not and then check if it contains any content, but Java has done that hard work for you. Well, it’s pretty easy to check emptiness for a file in Java by using length() method of the java. io. File class.

How check if file is empty C++?

The function tellg() returns the read (get) position of the file and we unveiled the file with the read (get) position at the end employing std::ios::ate . Hence in case tellg() returns 0 it should be empty.

How do you find a zero byte in Unix?

Zero size files

1. The ./ means start searching from the current directory. If you want to find files from another directory then replace the ./ with the path to needed directory. …
2. The -type f flag is specifies to find only files.
3. The -size 0 and -empty flags is specifies to find zero length files.

21 февр. 2015 г.

How can I tell if a file is open in Linux?

The command lsof -t filename shows the IDs of all processes that have the particular file opened. lsof -t filename | wc -w gives you the number of processes currently accessing the file.

How can I tell if a file transfer is complete in Linux?

If changing the source system is outside your control, you can use the “lsof” command. The Linux lsof command lists information about files that are open by processes running on the system. (The lsof command itself stands for “list of open files.”)

How do you check if a file is used by another process in Linux?

You can run lsof command on Linux filesystem and the output identifies the owner and process information for processes using the file as shown in the following output.

1. $ lsof /dev/null. List of All Opened Files in Linux. …
2. $ lsof -u tecmint. List of Files Opened by User. …
3. $ sudo lsof -i TCP:80. Find Out Process Listening Port.

29 мар. 2019 г.

What does grep return if nothing is found?

0 ]]; then echo “User does not exist!!” If grep fails to find a match it will exit 1 , so $? will be 1 . grep will always return 0 if successful.

Does grep support regex?

Grep Regular Expression

GNU grep supports three regular expression syntaxes, Basic, Extended, and Perl-compatible. In its simplest form, when no regular expression type is given, grep interpret search patterns as basic regular expressions.

What does grep command do?

grep is a command-line utility for searching plain-text data sets for lines that match a regular expression. Its name comes from the ed command g/re/p (globally search for a regular expression and print matching lines), which has the same effect.