snippetbashTip

entr — Run arbitrary commands when files change. See also: `watchexec`. More information: <https://eradman.

Submitted by: @import:tldr-pages·Mar 2, 2026·

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commandruncommandsfilesentrcliwhenarbitrary

Problem

How to use the entr command: Run arbitrary commands when files change. See also: watchexec. More information: <https://eradman.com/entrproject/>.

Solution

entr — Run arbitrary commands when files change. See also: watchexec. More information: <https://eradman.com/entrproject/>.

Rebuild with make if any file in any subdirectory changes:

{{ag --files-with-matches}} | entr {{make}}

Rebuild and test with make if any .c source files in the current directory change:

{{ls *.c}} | entr '{{make && make test}}'

Send a SIGTERM to any previously spawned ruby subprocesses before executing ruby main.rb:

{{ls *.rb}} | entr -r {{ruby main.rb}}

Run a command with the changed file (/_) as an argument:

{{ls *.sql}} | entr {{psql -f}} /_

[c]lear the screen and run a query after the SQL script is updated:

{{echo my.sql}} | entr -cp {{psql -f}} /_

Rebuild the project if source files change, limiting output to the first few lines:

{{find src/}} | entr -s '{{make | sed 10q}}'

Launch and auto-[r]eload a Node.js server:

{{ls *.js}} | entr -r {{node app.js}}

Code Snippets

Rebuild with `make` if any file in any subdirectory changes

{{ag --files-with-matches}} | entr {{make}}

Rebuild and test with `make` if any `.c` source files in the current directory change

{{ls *.c}} | entr '{{make && make test}}'

Send a `SIGTERM` to any previously spawned ruby subprocesses before executing `ruby main.rb`

{{ls *.rb}} | entr -r {{ruby main.rb}}

Run a command with the changed file (`/_`) as an argument

{{ls *.sql}} | entr {{psql -f}} /_

[c]lear the screen and run a query after the SQL script is updated

{{echo my.sql}} | entr -cp {{psql -f}} /_

Context

tldr-pages: common/entr

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