Write Current Date/Time to a File Using Shell Script

Write current date/time to a file using shell script

Use date >> //home/user/Desktop/Scripts/Date Logs/datelog.txt.

Like i tried in my system :-

date > /tmp/date.txt.
And file contains Wed Apr 5 09:27:37 IST 2017.

[Edit] There are difference between >>(appending to the file) and >(Create the new file)

Edit:- As suggested by chepner, you can directly redirect the o/p of date command to file using date >> /tmp/date.txt.

How to create a file with todays date in the filename

You should use double quotes and need to evaluate date +"%F" using command substitution.

  $ touch "test_$(date +%F)"

This will create an empty file test_2018-01-15

Double quote helps you create a single file where some options of date command would include a space.

For example, touch test_$(date) will create multiple files, where as touch "test_$(date)" won't.

As pointed out by OP, one would need additional quotes " around the format options, when multiple of them are used:

touch "test_$(date +"%F %T")" 

How to name a file with current time?

Use command substitution to capture date's output as a string.

echo 'hello' > "$(date +%T)".txt

Print a Date with some text in a new File using Shell Script

First of all you will want to format the output of date if you want to use it in the filename. If not you can use standard date command. You can find date format explanations here

Here is a sample block of code to output the current date and time to a text file :

#!/bin/bash

echo $(date +%F-%T) >> Output.txt

Here %F outputs the full date in the following format : YYYY-MM-DD

And %T outputs time in the following format : HH:MM:SS

If you want to add more text than just the date, you can use the " delimiter, to create a string as follow :

echo "$(date +%F-%T) Log output" >> Output.txt

Putting all the text in the string makes sure bash doesn't interpret what's inside the string as operators and delimiters.

EDIT : Screenshot for bash version :

How to get the current date and time in specific format in Shell

You may use:

dt=$(date '+%Y-%m-%dT%T.%zZ')
echo "$dt"

2019-02-27T04:35:56.-0500Z

Also note use of --iso-8601=seconds:

date --iso-8601=seconds

2019-02-27T04:37:29-05:00

YYYY-MM-DD format date in shell script

In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external date (usually GNU date).

As such:

# put current date as yyyy-mm-dd in $date
# -1 -> explicit current date, bash >=4.3 defaults to current time if not provided
# -2 -> start time for shell
printf -v date '%(%Y-%m-%d)T\n' -1 

# put current date as yyyy-mm-dd HH:MM:SS in $date
printf -v date '%(%Y-%m-%d %H:%M:%S)T\n' -1 

# to print directly remove -v flag, as such:
printf '%(%Y-%m-%d)T\n' -1
# -> current date printed to terminal

In bash (<4.2):

# put current date as yyyy-mm-dd in $date
date=$(date '+%Y-%m-%d')

# put current date as yyyy-mm-dd HH:MM:SS in $date
date=$(date '+%Y-%m-%d %H:%M:%S')

# print current date directly
echo $(date '+%Y-%m-%d')

Other available date formats can be viewed from the date man pages (for external non-bash specific command):

man date

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