44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
# Reading files
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spmenu is designed to read files. Most of the time it reads standard input
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which is also a file (/dev/stdin which is a symlink to /proc/self/fd/0 on
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systems using the Linux kernel). You don't necessarily have to read standard
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input or stdin though, as of spmenu 1.1 you can read any file you want.
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Reading from a file has benefits. When reading from standard input the entries
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are only loaded once. When reading from a file however, if the file is modified
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the new entries will be loaded and displayed on the next X11 event.
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## Reading from a file
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To read from any file you want, simply run spmenu with the `-lf` or
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`--list-file` argument. You can actually read from standard output using
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`--list-file` as well, by using `stdin | spmenu --list-file /dev/stdin`, but
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there is really no reason to do this as reading standard input is the default
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spmenu behavior anyway.
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For instance, `spmenu --list-file /tmp/file` would load entries from /tmp/file.
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## Real world use case
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Let's say we want to display the time and update it every second. In that case
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we can write a script like this:
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```
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#!/bin/sh
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func() {
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while true; do
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date > /tmp/date-file
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sleep 1
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done
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}
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func &
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spmenu -lf /tmp/date-file -p "The time is:"
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```
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[speedwm-extras](https://git.speedie.site/speedie/speedwm-extras)'
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speedwm-btctrl uses this feature to load Bluetooth entries every 5 seconds.
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There are more example scripts that also read from file in the
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`scripts/examples` directory.
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