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| If you want to help with the BashFAQ, you could try to answer one of the following questions. Just answer it, copy it to a new subpage of the BashFAQ page (e.g. [:BashFAQ/101:]), and remove the question here. | If you want to help with the BashFAQ, you could try to answer one of the following questions. Just answer it, copy it to a new subpage of the BashFAQ page (e.g. [[BashFAQ/101]]), and remove the question here. |
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| * It's also [:BashFAQ#faq45:Bash FAQ #45] now. | * It's also [[BashFAQ#faq45|Bash FAQ #45]] now. |
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| * {{{getopts}}}, or a while/shift loop (see [:BashFAQ#faq35:Bash FAQ #35]) | * {{{getopts}}}, or a while/shift loop (see [[BashFAQ#faq35|Bash FAQ #35]]) |
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| * Answer: {{{eval}}} -- see also [:BashFAQ#faq6:Bash FAQ #6] and the warnings in [:BashFAQ#faq48:#48]. * If {{{othervar}}} is an integer, use an [:BashFAQ#faq5:array] instead. |
* Answer: {{{eval}}} -- see also [[BashFAQ#faq6|Bash FAQ #6]] and the warnings in [[BashFAQ#faq48|#48]]. * If {{{othervar}}} is an integer, use an [[BashFAQ#faq5|array]] instead. |
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| * [:BashFAQ#faq70:FAQ #70] * How to redirect stderr to a pipeline? Now [:BashFAQ#faq47:Bash FAQ #47] |
* [[BashFAQ#faq70|FAQ #70]] * How to redirect stderr to a pipeline? Now [[BashFAQ#faq47|Bash FAQ #47]] |
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| Commands in a process substitution ( >(cmd) or <(cmd) ) are definitely run in a subshell. I'm not sure I understand what this question is really asking. Maybe it's related to [:BashFAQ#faq84:FAQ 84]. | Commands in a process substitution ( >(cmd) or <(cmd) ) are definitely run in a subshell. I'm not sure I understand what this question is really asking. Maybe it's related to [[BashFAQ#faq84|FAQ 84]]. |
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 a new subpage of the BashFAQ page (e.g. BashFAQ/101), 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 "$var" - quoting. See BashPitfalls for more.
- How can I ensure that only once instance of my script is running at a time?
Answer: e.g. lockfile. This should be answered in the UnixFaq
It's also Bash FAQ #45 now.
It's also covered in ProcessManagement.
- How can I handle command line arguments in a shell script?
getopts, or a while/shift loop (see Bash FAQ #35)
- How can I have variable variables, e.g. myvar=prefix$othervar?
Answer: eval -- see also Bash FAQ #6 and the warnings in #48.
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?
- This can't be done in any straightforward manner because there's no hook in Bash to execute arbitrary code after a user presses Enter but before a command is executed. The DEBUG trap is triggered after each command, and the PS1 variable is triggered when a prompt is displayed, which is also after the command, rather than before.
- How to determine Yesterday's date?
- date -d'yesterday' # GNU date
- date -r $(( $(date +%s) - 86400 )) # OpenBSD date
- How to convert Unix time stamps to a date (and vice versa)?
How to redirect stderr to a pipeline? Now Bash FAQ #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?
i think this does the job, have not had time to test: http://tldp.org/LDP/abs/html/process-sub.html
Commands in a process substitution ( >(cmd) or <(cmd) ) are definitely run in a subshell. I'm not sure I understand what this question is really asking. Maybe it's related to FAQ 84.