Date command in busybox not accepting formatted input date

busyboxdate

I want to set the date using busybox's date command (BusyBox v1.21.0).
My custom date to which I want to set the computer is of this form:

Tue, 15 Jan 2019 10:46:13 GMT

What my date command is capable of is to print out the date in the same format using this string:

date +"%a, %d %b %Y %T %Z"

It returns the date in the exact same format as above.
But It would not accept this when I use the -s option to set the date.

This fails for example:

date -u +"%a, %d %b %Y %T %Z" -s "Wed, 17 Feb 2010 19:14:32 UTC"
date: invalid date 'Wed, 17 Feb 2010 19:14:32 UTC'

I know busybox commands are reduced in function, but I imagined that when it can handle the format string to print the current date in the desired form, then it should also be able to use it to interpret an input string.

Best Answer

You can get busybox date to do the conversion of formats for you, using -D to specify the input format, and the usual +... for the output format, with -d providing the reference date and time. For example,

r='Tue, 15 Jan 2019 09:16:53 GMT'
d=$(busybox date -d "$r" -D "%a, %d %b %Y %T %Z" +'%Y-%m-%d %H:%M:%S')
# d becomes 2019-01-15 09:01:53
busybox date -s "$d"

Related Solutions

Shell – Leap seconds and date

I didn't find a simple solution to my question, so I've written a small Bash script to solve it. You need to download the leap seconds file given in the link below and put it with the script or change the path to it. I didn't write utc2unix.sh yet, but it's very easy to adapt. Do not hesitate to comment/give suggestions...

unix2utc.sh:

#!/bin/bash

# Convert a Unix timestamp to the real number of seconds
# elapsed since the epoch.

# Note: this script only manage additional leap seconds

# Download leap-seconds.list from
# https://github.com/eggert/tz/blob/master/leap-seconds.list

# Get current timestamp if nothing is given as first param
if [ -z $1 ]; then
    posix_time=$(date --utc +%s)
else
    posix_time=$1
fi

# Get the time at which leap seconds were added
seconds_list=$(grep -v "^#" leap-seconds.list | cut -f 1 -d ' ')

# Find the last leap second (see the content of leap-seconds.list)
# 2208988800 seconds between 01-01-1900 and 01-01-1970:
leap_seconds=$(echo $seconds_list | \
               awk -v posix_time="$posix_time" \
               '{for (i=NF;i>0;i--)
                   if (($i-2208988800) < posix_time) {
                    print i-1; exit
                    }
                } END {if (($(i+1)-2208988800) == posix_time) 
                    print "Warning: POSIX time ambiguity:",
                            posix_time,
                          "matches 2 values in UTC time!",
                          "The smallest value is given." | "cat 1>&2"
                }')
# echo $leap_seconds

# Add the leap seconds to the timestamp
seconds_since_epoch=$(($posix_time + $leap_seconds))

echo $seconds_since_epoch

Just some tests:

date --utc +%s && ./unix2utc.sh -> today and at least until June 2015 the difference is 25 sec.
./unix2utc.sh 78796799 -> 78796799
./unix2utc.sh 78796801 -> 78796802
./unix2utc.sh 78796800 -> 78796800 + on stderr: Warning: POSIX time ambiguity: 78796800 matches 2 consecutive values in UTC time! Only the smallest value is given.

Linux – How to Set Time with UNIX Timestamp Using BusyBox Date Command

Try

date @`date +%s`

I don't think it's got anything to do with bash.

Busybox's date command is a lightweight version of the more classic GNU/FSF date

Best Answer

Related Solutions

Shell – Leap seconds and date

Linux – How to Set Time with UNIX Timestamp Using BusyBox Date Command

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