tools: fix shellcheck errors.

Not sure how this got through Travis.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tools/check-markdown.sh

@@ -1,8 +1,7 @@
 #!/bin/bash
 
-diff -u <(egrep 'sudo apt-get install .*git' README.md) \
-     <(egrep 'sudo apt-get install .*git' doc/INSTALL.md)
-if [[ $? != 0 ]]; then
+if ! diff -u <(grep -E 'sudo apt-get install .*git' README.md) \
+     <(grep -E 'sudo apt-get install .*git' doc/INSTALL.md); then
     echo "Dependencies listed in README.md are not identical to those listed in doc/INSTALL.md (see above). Please fix."
     exit 1
 fi

tools/check-spelling.sh

@@ -1,7 +1,6 @@
 #!/bin/bash
 
-git --no-pager grep -nHiE 'l[ightn]{6}g|l[ightn]{8}g|ilghtning|lgihtning|lihgtning|ligthning|lighnting|lightinng|lightnnig|lightnign' -- . ':!tools/check-spelling.sh'
-if [[ $? == 0 ]]; then
+if git --no-pager grep -nHiE 'l[ightn]{6}g|l[ightn]{8}g|ilghtning|lgihtning|lihgtning|ligthning|lighnting|lightinng|lightnnig|lightnign' -- . ':!tools/check-spelling.sh'; then
     echo "Identified a likely misspelling of the word \"lightning\" (see above). Please fix."
     echo "Is this warning incorrect? Please teach tools/check-spelling.sh about the exciting new word."
     exit 1

tools/update-mocks.sh

@@ -9,8 +9,8 @@ FILE="$1"
 BASE=/tmp/mocktmp.$$.$(echo "$@" | tr / _)
 trap 'mv $BASE.old $FILE; rm -f $BASE.*' EXIT
 
-START=$(fgrep -n '/* AUTOGENERATED MOCKS START */' "$FILE" | cut -d: -f1)
-END=$(fgrep -n '/* AUTOGENERATED MOCKS END */' "$FILE" | cut -d: -f1)
+START=$(grep -F -n '/* AUTOGENERATED MOCKS START */' "$FILE" | cut -d: -f1)
+END=$(grep -F -n '/* AUTOGENERATED MOCKS END */' "$FILE" | cut -d: -f1)
 
 if [ -n "$START" ]; then
     mv "$FILE" "${BASE}.old"
@@ -21,7 +21,7 @@ if [ -n "$START" ]; then
     if ! make "${FILE/%.c/}" 2> "${BASE}.err" >/dev/null; then
 	tools/mockup.sh < "${BASE}.err" >> "${BASE}.stubs"
 	# If there are no link errors, maybe compile fail for other reason?
-	if ! fgrep -q 'Generated stub for' "${BASE}.stubs"; then
+	if ! grep -F -q 'Generated stub for' "${BASE}.stubs"; then
 	    cat "${BASE}.err"
 	    exit 1
 	fi