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| * How can I redirect the output of the script to both standard output and a log file? Answer: duplicating fds is not sufficient, because it duplicates the file descriptor number, not the data. But you can still use {{{tee}}}: {{{exec > >(tee log)}}} | * How can I redirect the output of the script to both standard output and a log file? * Duplicating fds is not sufficient, because it duplicates the file descriptor number, not the data. * But you can still use {{{tee}}}: {{{exec > >(tee log)}}} |
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| * How can I handle command line arguments in a shell script? Answer: {{{getopts(1)}}} | * How can I handle command line arguments in a shell script? * {{{getopts}}}, or a while/shift loop (see BashFaq #35) |
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| * How to determine Yesterday's date? Answer: date -d'yesterday' * How to convert Unix time stamps to a date (and vice versa)? Answer: GNU date, awk+strftime() * How to redirect stderr to a pipeline? (done: BashFaq #47 |
* How to determine Yesterday's date? * date -d'yesterday' # requires GNU date * How to convert Unix time stamps to a date (and vice versa)? * gdate -d "1970-01-01 UTC + $time seconds" * something involving awk and strftime() * perl -e "print scalar localtime $time, \"\n\"" * How to redirect stderr to a pipeline? Now BashFaq #47 |
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| * How can I redirect file names using sequential numbers to avoid overwriting existing ones? Answer: mv --backup=numbered | * How can I redirect file names using sequential numbers to avoid overwriting existing ones? * mv --backup=numbered # requires GNU mv * How can I set the output of a command to a variable without executing a subshell (i.e. $() ) or writing to a file and reading it back? |
Bash Open Questions
If you want to help with the BashFaq, you could try to answer one of the following questions. Just answer it, copy it to the BashFaq page, and remove the question here.
- How can I redirect the output of the script to both standard output and a log file?
- Duplicating fds is not sufficient, because it duplicates the file descriptor number, not the data.
But you can still use tee: exec > >(tee log)
- Somewhere the content of variables in my script lose whitespace.
echo "$var" - quoting. See BashPitfalls for more.
- How can I ensure that only once instance of my script is running at a time?
- How can I handle command line arguments in a shell script?
getopts, or a while/shift loop (see BashFaq #35)
- How can I have variable variables, e.g. myvar=prefix$othervar?
Answer: eval
If othervar is an integer, use an array instead.
- How can I make bash set the xterm title to the command it is currently executing?
- How to determine Yesterday's date?
- date -d'yesterday' # requires GNU date
- How to convert Unix time stamps to a date (and vice versa)?
- gdate -d "1970-01-01 UTC + $time seconds"
- something involving awk and strftime()
- perl -e "print scalar localtime $time, \"\n\""
How to redirect stderr to a pipeline? Now BashFaq #47
command 2>&1 | command
To discard stdout entirely: command 2>&1 >/dev/null | command
- How can I redirect file names using sequential numbers to avoid overwriting existing ones?
- mv --backup=numbered # requires GNU mv
- How can I set the output of a command to a variable without executing a subshell (i.e. $() ) or writing to a file and reading it back?