當我執行此代碼時，出現錯誤“awk: line 19: syntax error at or near”，我想知道如何定位錯誤發生的位置，第 19 行是注釋，所以第 19 行不是代碼中的第 19 行？我可以為這個問題做些什么？
TL;DR 我已經描述了我的問題，但我不能發帖，“看起來你的帖子主要是代碼；請添加更多細節。” 我必須寫這個……TAT
#!/bin/bash
#
# opensnoop - trace open() syscalls with file details.
# Written using Linux ftrace.
#
# This traces open() syscalls, showing the file name and returned file
# descriptor number (or -1, for error).
#
# This implementation is designed to work on older kernel versions, and without
# kernel debuginfo. It works by dynamic tracing of the return value of getname()
# as a string, and associating it with the following open() syscall return.
# This approach is kernel version specific, and may not work on your version.
# It is a workaround, and proof of concept for ftrace, until more kernel tracing
# functionality is available.
#
# USAGE: ./opensnoop [-htx] [-d secs] [-p pid] [-L tid] [-n name] [filename]
#
# Run "opensnoop -h" for full usage.
#
# REQUIREMENTS: FTRACE and KPROBE CONFIG, syscalls:sys_exit_open tracepoint,
# getname() kernel function (you may already have these on recent kernels),
# and awk.
#
# From perf-tools: https://github.com/brendangregg/perf-tools
#
# See the opensnoop(8) man page (in perf-tools) for more info.
#
# COPYRIGHT: Copyright (c) 2014 Brendan Gregg.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
# (http://www.gnu.org/copyleft/gpl.html)
#
# 20-Jul-2014 Brendan Gregg Created this.
### default variables
tracing=/sys/kernel/debug/tracing
flock=/var/tmp/.ftrace-lock; wroteflock=0
opt_duration=0; duration=; opt_name=0; name=; opt_pid=0; pid=; opt_tid=0; tid=
ftext=; opt_time=0; opt_fail=0; opt_file=0; file=
trap ':' INT QUIT TERM PIPE HUP # sends execution to end tracing section
function usage {
cat <<-END >&2
USAGE: opensnoop [-htx] [-d secs] [-p PID] [-L TID] [-n name] [filename]
-d seconds # trace duration, and use buffers
-n name # process name to match on open
-p PID # PID to match on open
-L TID # PID to match on open
-t # include time (seconds)
-x # only show failed opens
-h # this usage message
filename # match filename (partials, REs, ok)
eg,
opensnoop # watch open()s live (unbuffered)
opensnoop -d 1 # trace 1 sec (buffered)
opensnoop -p 181 # trace I/O issued by PID 181 only
opensnoop conf # trace filenames containing "conf"
opensnoop 'log$' # filenames ending in "log"
See the man page and example file for more info.
END
exit
}
function warn {
if ! eval "$@"; then
echo >&2 "WARNING: command failed \"$@\""
fi
}
function end {
# disable tracing
echo 2>/dev/null
echo "Ending tracing..." 2>/dev/null
cd $tracing
warn "echo 0 > events/kprobes/getnameprobe/enable"
warn "echo 0 > events/syscalls/sys_exit_open/enable"
warn "echo 0 > events/syscalls/sys_exit_openat/enable"
if (( opt_pid || opt_tid )); then
warn "echo 0 > events/kprobes/getnameprobe/filter"
warn "echo 0 > events/syscalls/sys_exit_open/filter"
warn "echo 0 > events/syscalls/sys_exit_openat/filter"
fi
warn "echo -:getnameprobe >> kprobe_events"
warn "echo > trace"
(( wroteflock )) && warn "rm $flock"
}
function die {
echo >&2 "$@"
exit 1
}
function edie {
# die with a quiet end()
echo >&2 "$@"
exec >/dev/null 2>&1
end
exit 1
}
### process options
while getopts d:hn:p:L:tx opt
do
case $opt in
d) opt_duration=1; duration=$OPTARG ;;
n) opt_name=1; name=$OPTARG ;;
p) opt_pid=1; pid=$OPTARG ;;
L) opt_tid=1; tid=$OPTARG ;;
t) opt_time=1 ;;
x) opt_fail=1 ;;
h|?) usage ;;
esac
done
shift $(( $OPTIND - 1 ))
if (( $# )); then
opt_file=1
file=$1
shift
fi
(( $# )) && usage
### option logic
(( opt_pid opt_name opt_tid > 1 )) && \
die "ERROR: use at most one of -p, -n, -L."
(( opt_pid )) && ftext=" issued by PID $pid"
(( opt_tid )) && ftext=" issued by TID $tid"
(( opt_name )) && ftext=" issued by process name \"$name\""
(( opt_file )) && ftext="$ftext for filenames containing \"$file\""
if (( opt_duration )); then
echo "Tracing open()s$ftext for $duration seconds (buffered)..."
else
echo "Tracing open()s$ftext. Ctrl-C to end."
fi
### select awk
(( opt_duration )) && use=mawk || use=gawk # workaround for mawk fflush()
[[ -x /usr/bin/$use ]] && awk=$use || awk=awk
### check permissions
cd $tracing || die "ERROR: accessing tracing. Root user? Kernel has FTRACE?
debugfs mounted? (mount -t debugfs debugfs /sys/kernel/debug)"
### ftrace lock
[[ -e $flock ]] && die "ERROR: ftrace may be in use by PID $(cat $flock) $flock"
echo $$ > $flock || die "ERROR: unable to write $flock."
wroteflock=1
### setup and begin tracing
echo nop > current_tracer
ver=$(uname -r)
if [[ "$ver" == 2.* || "$ver" == 3.[1-6].* ]]; then
# rval is char *
kprobe='r:getnameprobe getname 0($retval):string'
else
# rval is struct filename *
kprobe='r:getnameprobe getname 0( 0($retval)):string'
fi
if ! echo $kprobe >> kprobe_events; then
edie "ERROR: adding a kprobe for getname(). Exiting."
fi
if (( opt_pid )); then
filter=
for tid in /proc/$pid/task/*; do
filter="$filter || common_pid == ${tid##*/}"
done
filter=${filter:3} # trim leading ' || ' (four characters)
if ! echo $filter > events/kprobes/getnameprobe/filter || \
! echo $filter > events/syscalls/sys_exit_open/filter || \
! echo $filter > events/syscalls/sys_exit_openat/filter
then
edie "ERROR: setting -p $pid. Exiting."
fi
fi
if (( opt_tid )); then
if ! echo "common_pid == $tid" > events/kprobes/getnameprobe/filter || \
! echo "common_pid == $tid" > events/syscalls/sys_exit_open/filter || \
! echo "common_pid == $tid" > events/syscalls/sys_exit_openat/filter
then
edie "ERROR: setting -L $tid. Exiting."
fi
fi
if ! echo 1 > events/kprobes/getnameprobe/enable; then
edie "ERROR: enabling kprobe for getname(). Exiting."
fi
if ! echo 1 > events/syscalls/sys_exit_open/enable; then
edie "ERROR: enabling open() exit tracepoint. Exiting."
fi
if ! echo 1 > events/syscalls/sys_exit_openat/enable; then
edie "ERROR: enabling openat() exit tracepoint. Exiting."
fi
(( opt_time )) && printf "%-16s " "TIMEs"
printf "%-16.16s %-6s %4s %s\n" "COMM" "PID" "FD" "FILE"
#
# Determine output format. It may be one of the following (newest first):
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# TASK-PID CPU# TIMESTAMP FUNCTION
# To differentiate between them, the number of header fields is counted,
# and an offset set, to skip the extra column when needed.
#
offset=$($awk 'BEGIN { o = 0; }
$1 == "#" && $2 ~ /TASK/ && NF == 6 { o = 1; }
$2 ~ /TASK/ { print o; exit }' trace)
### print trace buffer
warn "echo > trace"
( if (( opt_duration )); then
# wait then dump buffer
sleep $duration
cat trace
else
# print buffer live
cat trace_pipe
fi ) | $awk -v o=$offset -v opt_name=$opt_name -v name=$name \
-v opt_duration=$opt_duration -v opt_time=$opt_time -v opt_fail=$opt_fail \
-v opt_file=$opt_file -v file=$file '
# common fields
$1 != "#" {
# task name can contain dashes and space
split($0, line, "-")
sub(/^[ \t\r\n] /, "", line[1])
comm = line[1]
if (opt_name && match(comm, name) == 0)
next
sub(/ .*$/, "", line[2])
pid = line[2]
}
# do_sys_open()
$1 != "#" && $(5 o) ~ /do_sys_open/ {
#
# eg: ... (do_sys_open 0xc3/0x220 <- getname) arg1="file1"
#
match($0, /arg1=\"(. )\"/, m)
lastfile[pid] = m[1]
}
# sys_open() / sys_openat()
$1 != "#" && ($(4 o) == "sys_open" || $(4 o) == "sys_openat") {
filename = lastfile[pid]
if (!filename)
next
delete lastfile[pid]
if (opt_file && filename !~ file)
next
rval = $NF
# matched failed as beginning with 0xfffff
if (opt_fail && rval !~ /0xfffff/)
next
if (rval ~ /0xfffff/)
rval = -1
if (opt_time) {
time = $(3 o); sub(":", "", time)
printf "%-16s ", time
}
printf "%-16.16s %-6s %4s %s\n", comm, pid, rval, filename
}
$0 ~ /LOST.*EVENTS/ {
delete lastfile
print "WARNING: " $0 > "/dev/stderr" }
'
### end tracing
end
uj5u.com熱心網友回復：
opensnoop有問題的行是shell 腳本末尾的大 awk 塊的第 19 行：
match($0, /arg1=\"(. )\"/, m)
lastfile[pid] = m[1]
為match（填充匹配項的陣列）提供第三個引數是gawk特定的語法，但作者似乎支持mawk和其他 awk 實作。
我用 mawk 測驗了 match() 行并得到了類似的錯誤（實際上是syntax error at or near ,- 即應該只有 2 個引數）
你gawk安裝了嗎？符號/usr/bin/awk鏈接到? mawk安裝/使用 gawk 可能會修復您的錯誤。
opensnoop使用 POSIX awk 語法編輯腳本也應該修復它：
match($0, /arg1=\"(. )\"/)
lastfile[pid] = substr($0, RSTART, RLENGTH)
但是，我只是簡要地查看了代碼，因此對此沒有任何保證。
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