diff --git a/Justfile b/Justfile
index 34d07a8b5..e3c83f223 100644
--- a/Justfile
+++ b/Justfile
@@ -491,7 +491,7 @@ STACKTEST := STACK + ' test --fast'
 @unittest:
     ($STACK exec hledger test && echo $@ PASSED) || (echo $@ FAILED; false)
 
-SHELLTEST := 'COLUMNS=80 ' + STACK + ' exec -- shelltest --execdir --exclude=/_ --threads=32'
+SHELLTEST := STACK + ' exec -- shelltest --execdir --exclude=/_ --threads=32'
 
 #  --hide-successes
 
diff --git a/doc/DEVWORKFLOWS.md b/doc/DEVWORKFLOWS.md
index 2c9817f76..4e7b423dd 100644
--- a/doc/DEVWORKFLOWS.md
+++ b/doc/DEVWORKFLOWS.md
@@ -224,10 +224,6 @@ stack's --file-watch flag will re-run build/test/bench when source files or pack
 
 If you find that adding --fast makes this any faster, please update this.
 
-## Use entr for watching arbitrary commands
-
-[entr](https://entrproject.org/) is the most robust cross-platform tool for watching files and running a command when they change. Note its first argument must be an executable program, to run a shell command or multiple commands use `bash -c "..."`.
-
 ### Rerun a single functional test as you change it:
 
-    ls hledger/test/budget/budget.test | entr bash -c 'clear; COLUMNS=80 stack exec -- shelltest --execdir hledger/test/budget/budget.test -i12'
+    watchexec -w hledger/test/journal/balance-assertions.test just functest -i budget.*19
\ No newline at end of file
diff --git a/hledger-ui/hledger-ui.m4.md b/hledger-ui/hledger-ui.m4.md
index 13dd0060d..4fd4498a7 100644
--- a/hledger-ui/hledger-ui.m4.md
+++ b/hledger-ui/hledger-ui.m4.md
@@ -347,10 +347,6 @@ clocks on both machines should be roughly in agreement.
 
 # ENVIRONMENT
 
-**COLUMNS**
-The screen width to use.
-Default: the full terminal width.
-
 **LEDGER_FILE**
 The main journal file to use when not specified with `-f/--file`.
 Default: `$HOME/.hledger.journal`.
diff --git a/hledger/Hledger/Cli/Commands/Register.md b/hledger/Hledger/Cli/Commands/Register.md
index 0d6b6aa52..04e629f15 100644
--- a/hledger/Hledger/Cli/Commands/Register.md
+++ b/hledger/Hledger/Cli/Commands/Register.md
@@ -148,9 +148,8 @@ no posting will be shown and the program exit code will be non-zero.
 
 ### Custom register output
 
-register uses the full terminal width by default, except on windows.
-You can override this by setting the `COLUMNS` environment variable (not a bash shell variable)
-or by using the `--width`/`-w` option.
+register normally uses the full terminal width (or 80 columns if it can't detect that).
+You can override this with the `--width`/`-w` option.
 
 The description and account columns normally share the space equally
 (about half of (width - 40) each). You can adjust this by adding a
@@ -165,10 +164,7 @@ and some examples:
 ```cli
 $ hledger reg                     # use terminal width (or 80 on windows)
 $ hledger reg -w 100              # use width 100
-$ COLUMNS=100 hledger reg         # set with one-time environment variable
-$ export COLUMNS=100; hledger reg # set till session end (or window resize)
 $ hledger reg -w 100,40           # set overall width 100, description width 40
-$ hledger reg -w $COLUMNS,40      # use terminal width, & description width 40
 ```
 
 This command also supports the
diff --git a/hledger/hledger.m4.md b/hledger/hledger.m4.md
index 6b435ba2a..8cd97483f 100644
--- a/hledger/hledger.m4.md
+++ b/hledger/hledger.m4.md
@@ -732,10 +732,8 @@ This is the default: human readable, plain text report output, suitable for view
 If your data contains unicode or wide characters, you'll need a terminal and font that render those correctly.
 (This can be challenging on MS Windows.)
 
-Some reports (`register`, `aregister`) will use the width indicated by the `COLUMNS` environment variable.
-If your shell and terminal are working well, they will keep COLUMNS updated as you resize the window.
-So register reports normally will use the full window width.
-When this isn't working or you want to override it, you can manually set COLUMNS, or use the `-w`/`--width` option.
+Some reports (`register`, `aregister`) will normally use the full window width.
+If this isn't working or you want to override it, you can use the `-w`/`--width` option.
 
 Balance reports (`balance`, `balancesheet`, `incomestatement`...) use whatever width they need.
 Multi-period multi-currency reports can often be wider than the window. Besides using a pager,
@@ -986,11 +984,6 @@ hledger bal --debug=3 2>hledger.log
 
 These environment variables affect hledger:
 
-**COLUMNS**
-This is normally set by your terminal;
-some hledger commands (`register`) will format their output to this width.
-If not set, they will try to use the available terminal width.
-
 **HLEDGER_LESS**
 If `less` is your [pager](#paging), this variable specifies the `less` options hledger should use.
 (Otherwise, `LESS` + custom options are used.)
diff --git a/hledger/test/README.md b/hledger/test/README.md
index 0f0cf1b01..7111c8d0a 100644
--- a/hledger/test/README.md
+++ b/hledger/test/README.md
@@ -38,25 +38,26 @@ around ghc 9.10's extra newline in error output: https://gitlab.haskell.org/ghc/
 
 Run them all (also builds hledger):
 
-    make functest
+    just functest
 
-See how the Makefile is invoking shelltestrunner:
+See the commands being run:
 
-    $ make functest -n
-    stack build --fast hledger
-    (COLUMNS=80 stack exec -- shelltest --execdir -j16 --hide-successes --exclude=/_ -w `stack exec -- which hledger` tests \
-            && echo functest PASSED) || (echo functest FAILED; false)
+    $ just -v functest
+    ===> Running recipe `functest`...
+    $STACK build --ghc-options=-Werror hledger
+    time ((stack exec -- shelltest --execdir --exclude=/_ --threads=32  hledger/test/ bin/ -x ledger-compat/ledger-baseline -x ledger-compat/ledger-regress -x ledger-compat/ledger-extra && echo $@ PASSED) || (echo $@ FAILED; false))
 
-These are the most important:
+Some explanation:
 
-- `COLUMNS=80` makes output independent of your terminal width.
-- `--execdir` runs each test within its own directory.
-- ``-w `stack exec -- which hledger` `` ensures you are testing the hledger executable that was just built.
-- `-j16` runs tests in parallel which is much faster.
+- `stack exec -- ...` ensures you are testing the hledger executable that was just built (it will be first in PATH).
+- `--execdir` executes tests within their test file's directory.
+- `--exclude=/_` excludes top-level test files whose names begin with underscore.
+- `--threads=N` runs tests in parallel which is much faster.
+- `-x` is another spelling of --exclude
 
-Run only the tests matching a regular expression (`balance-assertions:.*19` in this case):)
+Run only the tests matching a regular expression (here, the 19th test in the balance-assertions.test file):
 
-    $ make functest-balance-assertions.*19
+    $ just functest -i balance-assertions.*19
     :hledger/test/journal/balance-assertions.test:19: [OK]
 
              Test Cases  Total      
@@ -64,21 +65,9 @@ Run only the tests matching a regular expression (`balance-assertions:.*19` in t
      Failed  0           0          
      Total   1           1          
 
-Run only the tests in one file:
+Run a specific test repeatedly as its file is changed:
 
-    $ COLUMNS=80 shelltest --execdir -w `stack exec -- which hledger` hledger/test/cli/query-args.test
-    :hledger/test/cli/query-args.test:1: [OK]
-    :hledger/test/cli/query-args.test:2: [OK]
-    :hledger/test/cli/query-args.test:3: [OK]
-
-             Test Cases  Total      
-     Passed  3           3          
-     Failed  0           0          
-     Total   3           3          
-
-Run a test [repeatedly](http://eradman.com/entrproject/) as its file is changed:
-
-    $ ls hledger/test/cli/query-args.test | entr bash -c "COLUMNS=80 shelltest --execdir -w `stack exec -- which hledger` hledger/test/cli/query-args.test -i1"
+    $ watchexec -w hledger/test/journal/balance-assertions.test just functest -i balance-assertions.*19
     :hledger/test/cli/query-args.test:1: [OK]
 
              Test Cases  Total