Is there a way to add date in the name of the file... we can add current date in this manner date '+%Y%m%d' but i want to add "filename_date_1-2-2011_thru_31-2-2011.txt" Is it possible to do that??????????
If you have a sufficiently advanced version of the date command and you know a Unix timestamp for the start and end dates, then you can use:
(MacOS X) date -r 1234567890 "+%d-%m-%Y" to obtain 13-02-2009.
(GNU) date -d 2/13/2009 "+%d-%m-%Y" to obtain 13-02-2009 again.
If you don't want the leading zeroes on the day of month, then you need to use '%e` instead of '%d' on Linux (but that puts a space in place of the zero). It is not clear that there's a format specifier for day-of-month without a leading zero on MacOS X; nor is it clear that there's a way to format month of year as a single-digit number for January to September on either platform.
You get the format into your C shell script using back-ticks around the date commands.
Consider reading Csh Programming Considered Harmful and heeding its advice.
Related
date +'%A %B %d' | sed -e 's/\(^\|[^[:digit:]]\+\)0\+\([[:digit:]]\)/\1\2/g
I like the output of the above command, which strips leading zeroes off days of the month produced by the date command, in the case of numerals less than 10. It's the only way I've thus far found of producing single digit dates from the date command's output for the day of the month, which otherwise would be 01, 02, 03, etc.
A couple of questions in this regard. Is there a more elegant way of accomplishing the stated goal of stripping off zeroes? I do know about date's %e switch and would like to use it, but with numerals 10 and greater it has the undesirable effect of losing the space between the month name and the date (so, July 2 but July10).
The second question regards the larger intended goal of arriving at such an incantation. I'm putting together a script that will scrape some data from a web page. The best way of locating the target data on the page is by searching on the current date. But the site uses only single digits for the first 9 days of the month, thus the need to strip off leading zeroes. So what's the best way of getting this complex command into a variable so I can call it within my script? Would a variable within a variable be called for here?
RESOLUTION
I'll sort of answer my own question here, though it is really input from Renaud Pacalett (below) that enabled me to resolve the matter. His input revealed to me that I'd not understood very well the man page, particularly the part where is says "date pads numeric fields with zeroes," and below that where it is written "- (hyphen) do not pad the field." Had I understood better those statements, I would have realized that there is no need for the complex sed line through which I piped the date output in the title of this posting: had I used there %-d instead of just %d there would have been no leading zeroes in front of numerals less than 10 and so no need to call sed (or tr, as suggested below by LMC) to strip them off. In light of that, the answer to the second question about putting that incantation into a variable becomes elementary: var=$(date +'%A %B %-d') is all that is needed.
I may go ahead and mark Renaud Pacalet's response as the solution since, even though I did not implement all of his suggestions into the latest incarnation of my script, it proved crucial in clarifying key requirements of the task.
If your date utility supports it (the one from GNU coreutils does) you can use:
date +'%A %B %-d'
The - tells date to not pad the numeric field. Demo:
$ date -d"2021/07/01" +'%A %B %-d'
Thursday July 1
Not sure I understand your second question but if you want to pass this command to a shell script (I do not really understand why you would do that), you can use the eval shell command:
$ cat foo.sh
#!/usr/bin/env bash
foo="$(eval "$1")"
echo "$foo"
$ ./foo.sh 'date -d"2021/07/01" +"%A %B %-d"'
Thursday July 1
Please pay attention to the double (") and simple (') quotes usage. And of course, you will have to add to this example script what is needed to handle errors, avoid misuses...
Note that many string comparison utilities support one form or another of extended regular expressions. So getting rid of these leading zeros or spaces can be as easy as:
grep -E 'Thursday\s+July\s+0*1' foo.txt
This would match any line of foo.txt containing
Thursday<1 or more spaces>July<1 or more spaces><0 or more zeros>1
Is there any way to use standard tools (not programming scripts) to parse the date in custom, odd format?
I've got a start script (bash) that should handle the output of the program, that contains dates with very odd formatting (like Jan, 4, 2021, 1:20:30 PM - which would be a pattern like "MMM, d, yyyy, h:mm:ss a".
It would be possible to extract the tokens with sed or awk, but processing them is a nightmare, especially month shortcuts (they are in the same language like system, but that language can be installation-specific) or hours (need to check AM/PM token and add 12 if it's PM).
'date' apparently doesn't support that, but maybe some shell extension or toolkit package? Or I'm out of luck and I need to parse this crappy format token by token with sed/cut/awk?
This what I've tried was to do touch -d "Date" after removing the commas (so that I can compare dates with [[ file1 -ot file2 ]], but the problem is, that touch has ignored the TIME part, and ls -lh has shown, that the year was set in place of time, and the result of the comparison was therefore invalid.
Convert date with GNU date and bash:
d="Jan, 4, 2021, 1:20:30 PM"
IFS=',:' read mon day year hour min sec a <<<"$d"
date -d "$mon $day $year $hour:$min:$sec $a" '+%Y-%m-%d %H:%M:%S'
Output:
2021-01-04 13:20:30
I‘m aware of date +%u to get the day of the week for today.
I‘d like to get that integer for any arbitrary date i input - if possible in the format I choose (e.g. %YYmmdd)
ok, found it finally:
date -j -f %Y%m%d +%u 20200910
this is, because date on macOS doesn't take a switch for putting in custom date (fyi for those folks, how try to make -v work, like me^^)
in addition, -f affects only input format (it's literally the second word in the man page, but I managed to overlook more than once)
-j is needed to use -f without setting the date.
hope this will spare someone time in the future ;)
edit:
it seems to be important, to specify input format before output format (see comment from #chepner below)
(also be careful with quotes)
$ date +%u -d "2020-09-10"
4
I have a shell script where I ask the system to return the year, 660days ago. On my Mac, I use this:
date -j -v-660d +"%Y"
If run today, that would return 2011.
I'm moving the script to an Ubuntu machine, and I receive an error, stating that the -j and -v options are invalid.
I've looked at the man page, looking for equivalent options, but haven't been able to find a solution.
Any help is appreciated.
This should work:
$ date -d '660 days ago' +%Y
2011
Sometimes, there are more than one version of utilities like date. Oftentimes, the version shipped on Linux is not the same as the version shipped on BSD or macOS.
I found the man page for date on FreeBSD, and it says this:
-j Do not try to set the date. This allows you to use the -f flag
in addition to the + option to convert one date format to an-
other. Note that any date or time components unspecified by the
-f format string take their values from the current time.
-v [+|-]val[y|m|w|d|H|M|S]
Adjust (i.e., take the current date and display the result of the
adjustment; not actually set the date) the second, minute, hour,
month day, week day, month or year according to val. If val is
preceded with a plus or minus sign, the date is adjusted forwards
or backwards according to the remaining string, otherwise the
relevant part of the date is set. The date can be adjusted as
many times as required using these flags. Flags are processed in
the order given.
For the GNU version of date shipped on Linux, typically, the only way to set the date is to pass -s. So we don't need the -j flag. The GNU version of date has -d display the date describe by a passed string.
In your case, you want:
$ date -d '660 days ago' +%Y
2021
I am running some gnu time scripts which generates output of the form
mm:ss.mm (minutes, seconds and miliseconds, for example 1:20.66)
or hh:MM:ss (hours, minutes and seconds, for example 1:43:38).
I want to convert this to seconds (in order to compare them and plot them in a graphic).
Which is the easiest way to do this using bash?
$ TZ=utc date -d '1970-01-01 1:43:38' +%s
6218
Assuming you can run the GNU date command:
date +'%s' -d "01:43:38.123"
If the script is generating "mm:ss.mm" you'll need to add "00:" to the beginning, or date will reject it.
If you're on a BSD system (including Mac OS X), you need to run date -j +'%s' "0143.38" unless you have GNU date installed with MacPorts or Homebrew or something.
And if you want pure Bash you can do something like
IFS=: read h m s <<<"${hms%.*}"
seconds=$((10#$s+10#$m*60+10#$h*3600))
The 10# part is mandatory to specify that the numbers are given in radix 10. Without this, you'd get errors if h, m or s is 08 or 09 (as Bash interprets numbers with a leading 0 in octal).