[bash] History, use perl if installed otherwise awk (#3313)

While awk is POSIX, perl isn't pre-installed on all *nix flavors.
This commit eliminates the mandatory dependency on perl by using awk
when perl is not available.

Related: #3295, #3309, #3310.

Test suite passed:
* `make error` all test sections 'PASS'
* `make docker-test` 215 runs, 1884 assertions, 0 failures, 0 errors, 0 skips.

Manually tested in the following environments:
* Linux amd64 with bash 3.2, 4.4, 5.2; gawk -P, one true awk, mawk, busybox awk.
* macOS Catalina, bash 3.2, macOS awk 20070501.

**Performance comparison:**

Mawk turned out the fastest, then perl.
One true awk's implementation should be the closest to macOS awk.
Test data: 230 KB history, 15102 entries, including multi-line and duplicates.
Linux, bash 4.4. Times in milliseconds.

| Command                 | Mean | Min  | Max  | Relative |
| :---                    | ---: | ---: | ---: | -------: |
| `mawk 1.3.4`            | 22.9 | 22.3 | 25.6 | **1.00** |
| `perl 5.26.1`           | 34.3 | 33.6 | 35.1 |   1.49   |
| `one true awk 20221215` | 41.9 | 40.6 | 46.3 |   1.83   |
| `gawk 5.1.0`            | 46.1 | 44.4 | 50.3 |   2.01   |
| `busybox awk 1.27.0`    | 64.8 | 63.2 | 70.0 |   2.82   |

**Other Notes**

A bug affects bash, which fails restoring a saved multi-line history entry as a single entry. Bug fixed in version 5.0.[^1]

While developing this PR I discovered two unsubmitted issues affecting the current perl script. The output stream ends with `$'\n\0000'` instead of `$'\0000'`. Because of this, the script does not deduplicate a duplicated entry located at the end of the history list; therefore fzf displays two identical (not necessarily adjacent) entries. A minor point about the first issue is that the top fzf entry ends with a dangling line feed symbol, which is visible in the terminal.

[^1]: ec8113b986/CHANGES (L1511)
  To enable: `shopt -s cmdhist lithist; HISTTIMEFORMAT='%F %T '`.
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step 2023-09-22 10:37:34 +02:00 committed by GitHub
parent 2bed7d370e
commit 9f7684f6fe
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@ -48,7 +48,8 @@ __fzf_cd__() {
dir=$(set +o pipefail; eval "$cmd" | FZF_DEFAULT_OPTS="$opts" $(__fzfcmd)) && printf 'builtin cd -- %q' "$dir"
}
__fzf_history__() {
if command -v perl > /dev/null; then
__fzf_history__() {
local output opts script
opts="--height ${FZF_TMUX_HEIGHT:-40%} --bind=ctrl-z:ignore ${FZF_DEFAULT_OPTS-} -n2..,.. --scheme=history --bind=ctrl-r:toggle-sort ${FZF_CTRL_R_OPTS-} +m --read0"
script='BEGIN { getc; $/ = "\n\t"; $HISTCOUNT = $ENV{last_hist} + 1 } s/^[ *]//; print $HISTCOUNT - $. . "\t$_" if !$seen{$_}++'
@ -64,7 +65,39 @@ __fzf_history__() {
else
READLINE_POINT=0x7fffffff
fi
}
}
else # awk
__fzf_history__() {
local output opts script
if [[ -z $__fzf_awk ]]; then
__fzf_awk=awk
# if installed, mawk is faster
command -v mawk > /dev/null &&
mawk --version | # at least 1.3.4
awk 'NR == 1 { split($2, a, "."); v=(a[1]*1000000+ a[2]*1000+ a[3]*1); exit !(v >= 1003004) }' &&
__fzf_awk=mawk
fi
opts="--height ${FZF_TMUX_HEIGHT:-40%} --bind=ctrl-z:ignore ${FZF_DEFAULT_OPTS-} -n2..,.. --scheme=history --bind=ctrl-r:toggle-sort ${FZF_CTRL_R_OPTS-} +m --read0"
[[ $(HISTTIMEFORMAT='' builtin history 1) =~ [[:digit:]]+ ]] # how many history entries
script='function P(b) { ++n; sub(/^[ *]/, "", b); if (!seen[b]++) { printf "%d\t%s%c", '$((BASH_REMATCH + 1))' - n, b, 0 } }
NR==1 { b = substr($0, 2); next }
/^\t/ { P(b); b = substr($0, 2); next }
{ b = b RS $0 }
END { if (NR) P(b) }'
output=$(
set +o pipefail
builtin fc -lnr -2147483648 2> /dev/null | # ( $'\t '<lines>$'\n' )* ; <lines> ::= [^\n]* ( $'\n'<lines> )*
$__fzf_awk "$script" | # ( <counter>$'\t'<lines>$'\000' )*
FZF_DEFAULT_OPTS="$opts" $(__fzfcmd) --query "$READLINE_LINE"
) || return
READLINE_LINE=${output#*$'\t'}
if [[ -z "$READLINE_POINT" ]]; then
echo "$READLINE_LINE"
else
READLINE_POINT=0x7fffffff
fi
}
fi
# Required to refresh the prompt after fzf
bind -m emacs-standard '"\er": redraw-current-line'