Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
Bash
Kill Process by Port
When a port is "already in use" — find the offending process and (carefully) kill it. `lsof` is the gold standard; `ss` is the lighter modern alternative.
@admin
Bash
Background Jobs + wait
Run several commands in parallel with `&`, then wait for all of them with `wait`. Collect exit codes via $! and check after wait returns.
Bash
Trap Signals for Cleanup
Use `trap` to delete temp files / kill background workers when the script exits — even on Ctrl-C or an unhandled error. Single most-undervalued bash feature.
Bash
Check Command Exists Before Using It
`command -v` is the portable, fast way to check whether a binary is on $PATH. Avoid `which` (its behavior varies between systems).
Bash
Run Command with Timeout
`timeout` (GNU coreutils) kills a command after N seconds. Returns exit code 124 on timeout — let the caller distinguish "timed out" from "failed for other reasons."
Bash
PID File Management
Write a daemon's PID to a file at start, check on subsequent runs, clean up on exit. Avoids two copies of the same daemon when the script is invoked twice.
Bash
Process Substitution Cheatsheet
`<(...)` makes a command's output look like a file; `>(...)` makes a command's input look like a file. Killer feature for tools that only accept filenames.