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Need to know why crontab -e fails

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Top Forums Shell Programming and Scripting Need to know why crontab -e fails
# 1  
Old 12-12-2016
Bug Need to know why crontab -e fails
Code:
more cron.txt
1 * * * * /u/ways.sh 2>&1 >/dev/null

Code:
bash-4.1$ export EDITOR=vi
bash-4.1$ crontab -e <cron.txt
Vim: Warning: Input is not from a terminal
Vim: Error reading input, exiting...
Vim: Finished.
The crontab file was not changed.
bash-4.1$ echo $?
1

Code:
bash-4.1$ uname -a
SunOS mymac 5.11 11.2 sun4v sparc sun4v


Can you please explain why my crontab failed to add the entry in the cron.txt file.
# 2  
Old 12-12-2016
crontab -e is made for interactive input, and so is vi.
Two reasons for
Code:
crontab -e

No redirection from a file. In vi you can load the file with command
Code:
:r cron.txt

--
For non-interactive input from a file - without vi - you can do
Code:
crontab < cron.txt

that will replace the whole current crontab.
For non-interactive adding of crontab entries you can do
Code:
(crontab -l; cat cron.txt) | crontab

# 3  
Old 12-12-2016
Tools
Code:
(crontab -l; cat cron.txt) | crontab

This is what i was looking for ... but can i prevent it to append any entry from cron.txt into the crontab that is already present in the crontab ?
# 4  
Old 12-13-2016
grep out the existing entries!
For example grep out all the exact entries
Code:
(crontab -l | fgrep -vxf cron.txt; cat cron.txt) | crontab

---------- Post updated at 12:03 ---------- Previous update was at 12:02 ----------

If you want to regularly check for update, it is advisable to only replace the crontab if a change happens.
Code:
addto=$(
crontab -l | nawk 'FILENAME=="-" {A[$0]; next} !($0 in A)' - cron.txt
)
if [ -n "$addto" ]
then
  (crontab -l; echo "$addto") | crontab
fi

In theory you can also do a process substitution
Code:
addto=$(
fgrep -vxf <(crontab -l) cron.txt
)

but I have seen temporary malfunction in Solaris.
These 3 Users Gave Thanks to MadeInGermany For This Post:
Corona688 RavinderSingh13 rbatte1
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