106 lines
2 KiB
Markdown
106 lines
2 KiB
Markdown
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---
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tags:
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- Linux
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---
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## Use `&` to send a process to background
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Here is a dummy [process](./Processes.md):
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```sh
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bash -c 'while sleep 5; do echo "Still running... $(date +%T)"; done'
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```
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If I run this normally, it will continue to print every 5 seconds and I can't
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use the terminal.
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If I append `&` it will run in the background:
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```sh
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bash -c 'while sleep 5; do echo "Still running... $(date +%T)"; done' &
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# [1] 13134
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```
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It prints the job number (`[1]`) and the PID of the process.
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Now `stdout` will continue to interrupt every 5 seconds but I can do other
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things in the foreground, e.g:
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```
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~ bash -c 'while sleep 5; do echo "Still running... $(date +%T)"; done' &
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[2] 13505
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➜ ~ Still running... 18:20:42
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echo 'i can still use terminal'
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i can still use terminal
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➜ ~ Still running... 18:20:47
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Still running... 18:20:47
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```
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> Notice now I have two processes running (the same print script, twice), so the
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> job number has incremented to `[2]`
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## Bring a background process back to the foreground
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Use `%<job-number>` or `%<pid` to bring a process back to the foreground:
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```sh
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fg %1
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# [1] - 13134 running bash -c 'while sleep 5; do echo "Still running... $(date +%T)"; done'
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# Still running... 18:23:22
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# Still running... 18:23:22
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# Still running... 18:23:27
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```
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Now it's back in the foreground and I cannot use the terminal:
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```
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Still running... 18:24:17
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ls
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Still running... 18:24:22
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Still running... 18:24:22
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```
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## Pausing a job
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`Ctrl+Z` does not kill the process. It _pauses_ it. This moves it to the
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background and pauses its execution, returning terminal control back to you.
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For example I've stopped `vim` below:
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```
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vim minicom.log
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[1] + 14231 suspended nvim minicom.log
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```
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Again I'm given the job number.
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For it to continue in the background:
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```sh
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bg %1
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```
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Or the foreground:
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```sh
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fg %1
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```
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(This will reopen `vim`.)
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## Terminate a job
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```
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kill %1
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```
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## View jobs with `jobs`
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```
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jobs
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[1] + suspended nvim minicom.log
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[2] - running bash -c 'while sleep 5; do echo "Still running... $(date +%T)"; done'
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```
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