entr man page
entr — run arbitrary commands when files change
|entr|| [-cdprs] |
A list of files provided on the standard input and the
utility is executed using the supplied arguments if any of them change. entr waits for the child process to finish before responding to subsequent file system events. A TTY is also opened before entering the watch loop in order to support interactive utilities.
The arguments are as follows:
/usr/bin/clearbefore invoking the
utilityspecified on the command line.
Track the directories of regular files provided as input and exit if a new file is added. This option also enables directories to be specified explicitly. Files with names beginning with ‘
.’ are ignored.
Postpone the first execution of the
utilityuntil a file is modified.
Reload a persistent child process. SIGTERM is used to terminate the
utility before it is restarted.A process group is created to prevent shell scripts from masking signals. entr waits for the
utilityto exit to ensure that resources such as sockets have been closed.
Evaluate the first argument using the interpreter specified by the SHELL environment variable. When this flag is set, the name of the shell and exit code is printed after each invocation.
The first argument named
/_ is replaced with the absolute path of the file leading a file system event. If the restart option is used the first file under watch is treated as the default.
If PAGER is undefined, entr will assign
/bin/cat to prevent interactive utilities from waiting for keyboard input if output does not fit on the screen.
If SHELL is undefined, entr will use
The entr utility exits with one of the following values:
SIGINT or SIGTERM was received
No regular files were provided as input or an error occurred
A file was added to a directory and the directory watch option was specified
Rebuild a project if source files change, limiting output to the first 20 lines:
$ find src/ | entr -s 'make | head -n 20'
Launch and auto-reload a node.js server:
$ ls *.js | entr -r node app.js
Clear the screen and run a query after the SQL script is updated:
$ echo my.sql | entr -p psql -f /_
Rebuild project if a source file is modified or added to the src/ directory:
$ while true; do ls src/*.rb | entr -d make; done