1ENTR(1) BSD General Commands Manual ENTR(1)
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4 entr — run arbitrary commands when files change
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7 entr [-acdnprsz] utility [argument /_ ...]
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10 A list of files provided on standard input, and the utility is executed
11 using the supplied arguments if any of them change. entr waits for the
12 child process to finish before responding to subsequent file system
13 events. A TTY is also opened before entering the watch loop in order to
14 support interactive utilities.
15 The arguments are as follows:
17 -a Respond to all events which occur while the utility is running.
19 Without this option, entr consolidates events in order to avoid
20 looping. This option has no effect in conjunction with the -r
21 flag.
22 -c Clear the screen before invoking the utility specified on the
24 command line. Specify twice to erase the scrollback buffer.
25 -d Track the directories of regular files provided as input and exit
27 if a new file is added. This option also enables directories to
28 be specified explicitly. If specified twice, all new entries to
29 a directory are recognized, otherwise files with names beginning
30 with ‘.’ are ignored.
31 -n Run in non-interactive mode. In this mode entr does not attempt
33 to read from the TTY or change its properties.
34 -p Postpone the first execution of the utility until a file is modi‐
36 fied.
37 -r Reload a persistent child process. As with the standard mode of
39 operation, a utility which terminates is not executed again until
40 a file system or keyboard event is processed. SIGTERM is used to
41 terminate the utility before it is restarted. A process group is
42 created to prevent shell scripts from masking signals. entr
43 waits for the utility to exit to ensure that resources such as
44 sockets have been closed. Control of the TTY is not transferred
45 to the child process.
46 -s Evaluate the first argument using the interpreter specified by
48 the SHELL environment variable. If standard output is a TTY, the
49 name of the shell and exit code is printed after each invocation.
50 -z Exit after the utility completes. When combined with -r the
52 utility will be restarted again only in response to commands or
53 file system events.
54 The first argument named /_ is replaced with the absolute path of the
56 first file to trigger an event. The first file under watch is used as
57 the default. If the -s option is used, the name of the first file to
58 trigger an event can be read from $0.
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61 entr listens for keyboard input and responds to the following commands:
62 ⟨space⟩ Execute the utility immediately. If the -r option is set this
64 will terminate and restart the child process as if a file change
65 event had occurred.
66 q Quit; equivalent pressing ⟨control-C⟩.
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70 PAGER Set to /bin/cat by default to prevent interactive utilities
71 from waiting for keyboard input if output does not fit on
72 the screen.
73 SHELL Specify the shell to use with the -s flag. The default is
75 /bin/sh.
76 EV_TRACE Print file system event messages.
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80 If the -z flag is set and the utility is successfully executed, the sta‐
81 tus of the child process is returned. If the child process was termi‐
82 nated by a signal, the exit status is the signal number plus 128.
83 entr normally returns one of the following values:
85 0 Normal termination after receiving SIGINT
87 1 No regular files were provided as input or an error oc‐
88 curred
89 2 A file was added to a directory and the directory watch op‐
90 tion was specified
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93 Rebuild a project if source files change, limiting output to the first 20
94 lines:
95 $ find src/ | entr -s 'make | head -n 20'
97 Launch and auto-reload a node.js server:
99 $ ls *.js | entr -r node app.js
101 Clear the screen and run a query after the SQL script is updated:
103 $ echo my.sql | entr -cp psql -f /_
105 Rebuild project if a source file is modified or added to the src/ direc‐
107 tory:
108 $ while sleep 0.1; do ls src/*.rb | entr -d make; done
110 Auto-reload a web server, or terminate if the server exits
112 $ ls * | entr -rz ./httpd
114BSD August 1, 2023 BSD