To verify a valid date I use the command line below:
date -d "${DATE}" "+%Y/%m/%d" > /dev/null 2>&1
It works perfectly under Cygwin, but not in my test environment.
Here's some information about my test environment:
uname -a
AIX 152101a07e 3 5 00CDE2314C00
Using the command line:
echo $?
The result is always 1, even if the date is valid.
Do you have any idea why this test fails?
Apparently, your two environments are not running the same version of date. You should check the man page for date in your new environment (run man date). On my machine (OS X), the -d option is used for setting daylight savings time.
For example, the following works for me:
date -j -f "%Y/%m/%d" "2014/07/09" > /dev/null 2>&1
echo $? # 0
date -j -f "%Y/%m/%d" "2014.07.09" > /dev/null 2>&1
echo $? # 1
-j tells it to not try to set my system date. -f means to use the specified format.
Yours may be different, but you can find out the details by reading the manual.
Related
Currently, I am using cloud VMs to run my code and because of that I am assigned with a new VM that is in a different time zone. I want to run a bash script that runs a python script at 7:30 pm (Eastern time). From here I know how to run a bash script at a specific time, e.g., echo "ls -l" | at 07:00. From here I know how to get the current time of Eastern time, e.g., TZ=America/New_York date. Also, from here I know how to get only the time using date +%R.
I am a Python coder and tried my best to write a sudo code that shows what I am trying to accomplish as a bash script:
while true
do
Now=TZ=America/New_York date +%R
if [Now -eq 7:30pm]
then
python3 myfile.py
done
As you already know how to set the at command to execute a command
at the specified time, and how to convert the EST to the local time,
you can just combine them:
echo "python3 myfile.py" | at $(date -d "19:30 EST" +%R)
When you invoke the at command, it always warns
"commands will be executed using /bin/sh". It will matter only if we invoke
a bash specific command such as:
echo "shopt -s globstar; ls **" | at ..
which will fail.
In our case, the command python3 myfile.py will run with both
/bin/sh and /bin/bash then you do not worry about the warning.
date -d STRING interprets the STRING as a date/time representation
and prints the converted date/time in the specified format +%R.
If you want to send the output to a file, you can say:
echo "python3 myfile.py > /path/to/a/file" | at $(date -d "19:30 EST" +%R)
In order to output to the current terminal, first identify the terminal
with tty command:
$ tty
=> /dev/pts/0
Then redirect the output to the terminal with:
echo "python3 myfile.py > /dev/pts/0" | at $(date -d "19:30 EST" +%R)
I made this simple bash script to take a full-screen screenshot and save it to the pictures folder
#!/usr/bin/bash
xfce4-screenshooter -f -s /home/rgcodes/Pictures/Screenshot_$scrshotcount.png
let "scrshotcount++"
...which runs into a problem. scrshotcount is a global variable I defined in /etc/environment to be incremented every time the script runs. However, the script fails to increment the variable globally, and causes the script to just overwrite the previous screenshot. Searches on Google and Stack Overflow revealed that the problem isn't straightforward at all (something about child shells being unable to change variables for parents), and finding some other method would be better.
Here's my question. How do we append numbers (in ascending order) to the screenshots the script throws out so that they are saved just like those taken on Windows?(Windows auto-suffixes matching filenames, rather than overwriting them, so all Screenshots have the same name 'Screenshot' and the number of times the screenshot command has been used.)
I am using #erikMD's method as a temporary stop-gap for now.
In addition to the excellent advice about using a date instead of a counter, here's a way to use a counter :/
dir=$HOME/Pictures
# find the current maximum value
current_max=$(
find "$dir" -name Screenshot_\*.png -print0 \
| sort -z -V \
| tail -z -n 1
)
if [[ ! $current_max =~ _([0-9]+)\.png ]]; then
echo "can't find the screenshot with the maximum counter value" >&2
exit 1
fi
# increment it
counter=$(( 1 + ${BASH_REMATCH[1]} ))
# and use it
xfce4-screenshooter -f -s "$dir/Screenshot_${counter}.png"
You'll have to manually create the Screenshot_1.png file.
#rgcodes below is a script that will capture screenshots with a numeric count indicator per your original post. (tested it on Ubuntu 20.04)
Script contents:
#!/bin/bash
set -uo pipefail
# add source file and line number to xtrace output
# i.e. when running: bash -x ./your_script_name.sh
export PS4='+(${BASH_SOURCE}:${LINENO}): ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
capture_screenshot() {
local output_dir="${1:-/tmp/screenshot}"
local img_name="${2:-Screenshot}"
local img_ext="${3:-png}"
# create output directory (if not already existing)
mkdir -p "${output_dir}"
# get the last image in the sorted ls output
local latest_png=$(tail -n 1 \
<(sort -n -t _ -k 2 \
<(ls ${output_dir}/*.${img_ext} 2> /dev/null)))
# use the latest image to determine img_cnt value for next image
local img_cnt=0
if [[ ${latest_png} =~ _([0-9]+)\.png ]]; then
img_cnt=$((1+${BASH_REMATCH[1]}))
elif [[ ${latest_png} =~ ${img_name}.${img_ext} ]] ; then
img_cnt=1
fi
# build path to output image
local img_path="${output_dir}/${img_name}_${img_cnt}.${img_ext}"
# remove count from output image path if count == 0
if [[ "${img_cnt}" -eq "0" ]] ; then
img_path="${output_dir}/${img_name}.${img_ext}"
fi
xfce4-screenshooter -f -s "${img_path}"
}
capture_screenshot "$#"
The uses the following as defaults, but you can change them to meet your requirements.
output directory for screenshots:
/tmp/screenshot
base screenshot image name:
Screenshot
screenshot file extension:
.png
The script will attempt to create the output directory if it does not already exist (subject to user permission for creation). Below is a sample usage.
Prior to initial script execution, the output directory does not exist:
$ ls screenshot
$
Initial execution (directory is created and Screenshot.png created:
$ ./script.sh
$ ls /tmp/screenshot/
Screenshot.png
Subsequent executions:
$ ./script.sh
$ ls /tmp/screenshot/
Screenshot_1.png Screenshot.png
$ ./script.sh
$ ls /tmp/screenshot/
Screenshot_1.png Screenshot_2.png Screenshot.png
Indeed, as suggested by #j_b in the comments, you should definitely give a try to using a timestamp with the command date +"$format".
FTR, the same idea is implemented here in this project of a gnome-screenshot bash wrapper
(disclaimer: I am the author of this repo).
Example command:
date "+%Y-%m-%d_%H-%M-%S"
↓
2021-07-29_19-13-30
So the overall script could just be something like:
#!/usr/bin/env bash
xfce4-screenshooter -f -s "$HOME/Pictures/Screenshot_$(date "+%Y-%m-%d_%H-%M-%S").png"
(Note that I added missing double-quotes, and modified your shebang, as /usr/bin/env bash is more portable than /bin/bash or /usr/bin/bash.)
I use a combination of stat and touch for getting/setting timestamps on files and repertories. But I need different set-ups if on mac os x or GNU/Linux:
touch on mac os x does not know the -d option described there
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/touch.html
which allows things like
touch -d "2007-11-12 10:15:30.002Z" ajosey
I am seemingly constrained to -t [[CC]YY]MMDDhhmm[.SS].
stat also differs, for example on a Linux account of mine, it does not recognize the -t format from the stat on mac os x.
Thus on the Linux I currently do something like
stat --format 'touch -d "%y" "%n"' index.html
to create a command line of the type
touch -d "2015-04-08 00:38:51.940365000 +0200" "index.html"
whereas on the mac os x I have
stat -f "touch -t %Sm \"%N\"" -t %Y%m%d%H%M.%S index.html
which gives me something (this is not the same index.html as prior) like:
touch -t 201503281339.42 "index.html"
How could handle this in a unified way ? Perhaps with some sed in between ?
I need to produce a sequence of touch commands in a format working on both platforms. The creation of this sequence must work on both platforms.
I am open to other scripting than bash, with the constraint that on the Linux side I am with a system with no admin rights. perl there is This is perl, v5.10.1 (*) built for x86_64-linux-thread-multi.
Short of a better method, I will temporarily adopt the following, which is based on these observations:
touch -t works the same on my mac os x and the Linux I have access too.
On the Linux side, I can use date -d to transform a date as produced by stat -c %y to the YYYYMMDDHHMM.SS format I can use on input to touch -t, and on the Mac OS X side I can use directly stat with suitable options for this result.
For batch processing of files in a repertory, where I was using stat with * shell expansion, I can replace that with a for shell loop.
Putting these things together I end with the following script:
#!/bin/sh
case `uname -s` in
"Linux" )
MYDATEFORTOUCH() {
date -d"$(stat -c %y "$1")" +%Y%m%d%H%M.%S
}
;;
"Darwin" )
MYDATEFORTOUCH() {
stat -f %Sm -t %Y%m%d%H%M.%S "$1"
}
;;
* )
MYDATEFORTOUCH() {
197001010000.00
}
;;
esac
echo "#!/bin/sh" > fichierTEMPA
for file in *
do echo "touch -ch -t $(MYDATEFORTOUCH "$file") \"$file\"" >> fichierTEMPA
done
Executing this in a repertory produces a file (with silly name here fichierTEMPA) which is a series of touch -t commands. The -h is for not following symbolic links, on mac os x, it implies the -c which is to not create a file which didn't exist, I am not sure if -c is also implied by -h on GNU/Linux.
Install the GNU Coreutils on your Mac and you can stop bothering about incompatibilities. It is explained here how to do it.
TASK - SSH to 650 Servers and fetch few details from them and then write the completed server name in different file. How can do it in faster way? If I do normal ssh it takes 7 Minutes. So, I read about awk and wrote following 2 codes.
Could you please explain me the difference in the following codes?
Code 1 -
awk 'BEGIN{done_file="/home/sarafa/AWK_FASTER/done_status.txt"}
{
print "blah"|"ssh -o StrictHostKeyChecking=no -o BatchMode=yes -o ConnectTimeout=1 -o ConnectionAttempts=1 "$0" uname >/dev/null 2>&1";
print "$0" >> done_file
}' /tmp/linux
Code 2 -
awk 'BEGIN{done_file="/home/sarafa/AWK_FASTER/done_status.txt"}
{
"ssh -o StrictHostKeyChecking=no -o BatchMode=yes -o ConnectTimeout=1 -o ConnectionAttempts=1 "$0" uname 2>/dev/null"|getline output;
print output >> done_file
}' /tmp/linux
When I run these codes for 650 Servers, Code 1 takes - 30 seconds and Code 2 takes 7 Minutes ?
Why is there so much time difference ?
File - /tmp/linux is a list of 650 servers
Updated Answer - with thanks to #OleTange
This form is preferable to my suggestion:
parallel -j 0 --tag --slf /tmp/linux --nonall 'hostname;ls'
--tag Tag lines with arguments. Each output line will be prepended
with the arguments and TAB (\t). When combined with --onall or
--nonall the lines will be prepended with the sshlogin
instead.
--nonall --onall with no arguments. Run the command on all computers
given with --sshlogin but take no arguments. GNU parallel will
log into --jobs number of computers in parallel and run the
job on the computer. -j adjusts how many computers to log into
in parallel.
This is useful for running the same command (e.g. uptime) on a
list of servers.
Original Answer
I would recommend using GNU Parallel for this task, like this:
parallel -j 64 -k -a /tmp/linux 'echo ssh user#{} "hostname; ls"'
which will ssh into 64 hosts in parallel (you can change the number), run hostname and ls on each and then give you all the results in order (-k switch).
Obviously remove the echo when you see how it works.
I have an old Syno NAS and wish to use the "shred" command to wipe this disks inside. The idea is to let the command run to complete on the box itself without the need of a computer.
So far I have managed...
1) to get the right parameters for 'shred'
* runs in the background using the &
2) get that command to output the progress (-v option) to a file shred.txt
* to see from the file what the progress is
shred -v -f -z -n 2 /dev/hdd 2>&1 | tee /volume1/backup/shred.txt &
3) ssh tunnel the command so I can turn off my laptop while its running
ssh -n -f root#host "sh -c 'nohup /opt/bin/shred -f -z -n 2 /dev/sdd > /dev/null 2>&1 &'"
The problem is that I can't combine 2) and 3)
I tried to combine them like this, but the resulting file remained empty:
ssh -n -f root#host "sh -c 'nohup /opt/bin/shred -f -z -n 2 /dev/sdd 2>&1 | tee /volume1/backup/shred.txt > /dev/null &'"
It might be a case of the NOOBS but I can't figure out how to get this done.
Any suggestions?
Thanks. Vince
Commands sh and tee are not needed in here:
ssh -n root#host 'nohup /opt/bin/shred -f -z -n 2 /dev/sdd 2>&1 >/volume1/backup/shred.txt &' >/dev/null
The final >/dev/null is optional, it will just disregard any greetings from other hosts.
Tried the following command (based on Grzegorz suggestion) and included the opening date stamp and the before mentioned - stupidly forgotten - verbose switch. Last version of the command string:
ssh -n root#host 'date > /volume1/backup/shred_sda.txt; nohup /opt/bin/shred -v -f -z -n 4 /dev/sda 2>&1 >> /volume1/backup/shred_sda.txt # >/dev/null'
The last thing to figure out is how to include the date stamp when the shred command has completed.