What does -f mean in bash

I was looking at how to use runit to run gunicorn. I was looking at the bash file and I don't know what -f $PID does in

#!/bin/sh GUNICORN=/usr/local/bin/gunicorn ROOT=/path/to/project PID=/var/run/gunicorn.pid APP=main:application if [ -f $PID ]; then rm $PID; fi cd $ROOT exec $GUNICORN -c $ROOT/gunicorn.conf.py --pid=$PID $APP 

Google is useless in this case because searching for flags is useless

5 Answers

Google is useless in this case because searching for flags is useless

Fortunately, the Bash Reference Manual is available online, at . It's the first hit when you Google for "Bash manual". §6.4 "Bash Conditional Expressions" says:

-f file

True if file exists and is a regular file.

-f - file is a regular file (not a directory or device file)

Check this out for all file test operators:

The [ is the same as the command test which allows you to test certain things. Try help test to find out what the flags are. Things to be careful with are spaces - the [ needs a space after it.

-f checks if the file exists and is a regular file.

[ -f "$var" ] 

Checks if $var is an existing file (regular file). Symbolic link passes this test too.