16.1 \u7b97\u672f\u8fd0\u7b97\u65b9\u6cd5<\/p>\n\n\n\n
shell\u4e2d\u5982\u4f55\u8fdb\u884c\u7b97\u672f\u8fd0\u7b97\uff1a<\/p>\n\n\n\n
A=3<\/p>\n\n\n\n
B=6<\/p>\n\n\n\n
1\u3001let \u7b97\u672f\u8fd0\u7b97\u8868\u8fbe\u5f0f<\/p>\n\n\n\n
let C=$A+$B<\/p>\n\n\n\n
2\u3001$[\u7b97\u672f\u8fd0\u7b97\u8868\u8fbe\u5f0f]<\/p>\n\n\n\n
C=$[$A+$B]<\/p>\n\n\n\n
3\u3001$((\u7b97\u672f\u8fd0\u7b97\u8868\u8fbe\u5f0f))<\/p>\n\n\n\n
C=$(($A+$B))<\/p>\n\n\n\n
4\u3001expr \u7b97\u672f\u8fd0\u7b97\u8868\u8fbe\u5f0f\uff0c\u8868\u8fbe\u5f0f\u4e2d\u5404\u64cd\u4f5c\u6570\u53ca\u8fd0\u7b97\u7b26\u4e4b\u95f4\u8981\u6709\u7a7a\u683c\uff0c\u800c\u4e14\u8981\u4f7f\u7528\u547d\u4ee4\u5f15\u7528<\/p>\n\n\n\n
C=`expr $A + $B`<\/p>\n\n\n\n
16.2 \u6d4b\u8bd5\u65b9\u6cd5\uff1a<\/p>\n\n\n\n
[ expression ]<\/p>\n\n\n\n
[[ expression ]]<\/p>\n\n\n\n
test expression<\/p>\n\n\n\n
bash\u4e2d\u5e38\u7528\u7684\u6761\u4ef6\u6d4b\u8bd5\u6709\u4e09\u79cd\uff1a<\/p>\n\n\n\n
16.2.1 \u6574\u6570\u6d4b\u8bd5\uff1a<\/p>\n\n\n\n
-gt\uff1a\u5927\u4e8e<\/p>\n\n\n\n
-le\uff1a\u5c0f\u4e8e\u7b49\u4e8e<\/p>\n\n\n\n
-ne\uff1a\u4e0d\u7b49\u4e8e<\/p>\n\n\n\n
-eq\uff1a\u7b49\u4e8e<\/p>\n\n\n\n
-ge<\/p>\n\n\n\n
-lt<\/p>\n\n\n\n
\u6d4b\u8bd5\u4e24\u4e2a\u6574\u6570\uff08\u53ea\u6709\u8fdb\u884c\u6574\u6570\u6d4b\u8bd5\u65f6\u624d\u80fd\u7528[]\uff0c\u5176\u4ed6\u60c5\u51b5\u4e00\u5b9a\u4e0d\u80fd\u52a0\uff09<\/p>\n\n\n\n
INT1=63<\/p>\n\n\n\n
INT2=77<\/p>\n\n\n\n
[ $INT1 -eq $INI2 ]<\/p>\n\n\n\n
[[ $INT1 -eq $INT2 ]]<\/p>\n\n\n\n
test $INT1 -eq $INT2 <\/p>\n\n\n\n
16.2.2 \u6587\u4ef6\u6d4b\u8bd5\uff1a <\/p>\n\n\n\n
-e FILE\uff1a\u6d4b\u8bd5\u6587\u4ef6\u662f\u5426\u5b58\u5728<\/p>\n\n\n\n
-f FILE: \u6d4b\u8bd5\u6587\u4ef6\u662f\u5426\u4e3a\u666e\u901a\u6587\u4ef6<\/p>\n\n\n\n
-d FILE: \u6d4b\u8bd5\u6307\u5b9a\u8def\u5f84\u662f\u5426\u4e3a\u76ee\u5f55<\/p>\n\n\n\n
-r FILE: \u6d4b\u8bd5\u5f53\u524d\u7528\u6237\u5bf9\u6307\u5b9a\u6587\u4ef6\u662f\u5426\u6709\u8bfb\u53d6\u6743\u9650\uff1b<\/p>\n\n\n\n
-w FILE: \u6d4b\u8bd5\u5f53\u524d\u7528\u6237\u5bf9\u6307\u5b9a\u6587\u4ef6\u662f\u5426\u6709\u5199\u6743\u9650\uff1b<\/p>\n\n\n\n
-x FILE: \u6d4b\u8bd5\u5f53\u524d\u7528\u6237\u5bf9\u6307\u5b9a\u6587\u4ef6\u662f\u5426\u6709\u6267\u884c\u6743\u9650\uff1b<\/p>\n\n\n\n
\u4f8b\uff1a<\/p>\n\n\n\n
[ -e \/etc\/inittab ]<\/p>\n\n\n\n
[ -x \/etc\/rc.d\/rc.sysinit ] <\/p>\n\n\n\n
\u7ec3\u4e60\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u7ed9\u5b9a\u4e00\u4e2a\u6587\u4ef6\uff1a<\/p>\n\n\n\n
\u5982\u679c\u662f\u4e00\u4e2a\u666e\u901a\u6587\u4ef6\uff0c\u5c31\u663e\u793a\u4e4b\uff1b<\/p>\n\n\n\n
\u5982\u679c\u662f\u4e00\u4e2a\u76ee\u5f55\uff0c\u4ea6\u663e\u793a\u4e4b\uff1b<\/p>\n\n\n\n
\u5426\u5219\uff0c\u6b64\u4e3a\u65e0\u6cd5\u8bc6\u522b\u4e4b\u6587\u4ef6\uff1b<\/p>\n\n\n\n
16.3 \u5b9a\u4e49\u811a\u672c\u9000\u51fa\u72b6\u6001\u7801<\/p>\n\n\n\n
exit: \u9000\u51fa\u811a\u672c<\/p>\n\n\n\n
exit #<\/p>\n\n\n\n
\u5982\u679c\u811a\u672c\u6ca1\u6709\u660e\u786e\u5b9a\u4e49\u9000\u51fa\u72b6\u6001\u7801\uff0c\u90a3\u4e48\uff0c\u6700\u540e\u6267\u884c\u7684\u4e00\u6761\u547d\u4ee4\u7684\u9000\u51fa\u7801\u5373\u4e3a\u811a\u672c\u7684\u9000\u51fa\u72b6\u6001\u7801\uff1b<\/p>\n\n\n\n
\u6d4b\u8bd5\u811a\u672c\u662f\u5426\u6709\u8bed\u6cd5\u9519\u8bef\uff1a<\/p>\n\n\n\n
bash -n \u811a\u672c\uff08\u4e0d\u80fd\u4f5c\u4e3a\u5224\u65ad\u4f9d\u636e\uff0c\u53ea\u80fd\u7528\u6765\u53c2\u8003\uff09<\/p>\n\n\n\n
bash -x \u811a\u672c\uff1a\u5355\u6b65\u6267\u884c<\/p>\n\n\n\n
16.4 bash\u53d8\u91cf\u7684\u7c7b\u578b\uff1a<\/p>\n\n\n\n
(1)\u672c\u5730\u53d8\u91cf(\u5c40\u90e8\u53d8\u91cf)<\/p>\n\n\n\n
(2)\u73af\u5883\u53d8\u91cf<\/p>\n\n\n\n
(3)\u4f4d\u7f6e\u53d8\u91cf: <\/p>\n\n\n\n
$1, $2, …\uff08\u8868\u793a\u811a\u672c\u7684\u7b2cn\u4e2a\u53c2\u6570\uff09<\/p>\n\n\n\n
.\/filetest.sh \/etc\/fstab \/etc\/inittab<\/p>\n\n\n\n
$1: \/etc\/fstab<\/p>\n\n\n\n
$2: \/etc\/inittab<\/p>\n\n\n\n
shift\uff1a\u8f6e\u6362\u8f6e\u66ff<\/p>\n\n\n\n
[daniel@localhost tmp]$ vim shift.sh<\/p>\n\n\n\n
[daniel@localhost tmp]$ chmod +x shift.sh <\/p>\n\n\n\n
[daniel@localhost tmp]$ .\/shift.sh <\/p>\n\n\n\n
[daniel@localhost tmp]$ .\/shift.sh 1 2 3<\/p>\n\n\n\n
1<\/p>\n\n\n\n
2<\/p>\n\n\n\n
3<\/p>\n\n\n\n
[daniel@localhost tmp]$ help shift<\/p>\n\n\n\n
shift: shift [n]<\/p>\n\n\n\n
Shift positional parameters.<\/p>\n\n\n\n
Rename the positional parameters $N+1,$N+2 … to $1,$2 … If N is<\/p>\n\n\n\n
not given, it is assumed to be 1.<\/p>\n\n\n\n
Exit Status:<\/p>\n\n\n\n
Returns success unless N is negative or greater than $#.<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
#<\/p>\n\n\n\n
echo $1<\/p>\n\n\n\n
shift<\/p>\n\n\n\n
echo $1<\/p>\n\n\n\n
shift<\/p>\n\n\n\n
echo $1<\/p>\n\n\n\n
(4)\u7279\u6b8a\u53d8\u91cf\uff1a<\/p>\n\n\n\n
$?:\u4e0a\u4e00\u6761\u547d\u4ee4\u7684\u9000\u51fa\u72b6\u6001\u7801<\/p>\n\n\n\n
$#\uff1a\u53c2\u6570\u7684\u4e2a\u6570<\/p>\n\n\n\n
$*: \u53c2\u6570\u5217\u8868<\/p>\n\n\n\n
$@\uff1a\u53c2\u6570\u5217\u8868<\/p>\n\n\n\n
\u7ec3\u4e601\uff1a\u5199\u4e00\u811a\u672c<\/p>\n\n\n\n
\u80fd\u63a5\u53d7\u4e00\u4e2a\u53c2\u6570(\u6587\u4ef6\u8def\u5f84)<\/p>\n\n\n\n
\u5224\u5b9a\uff1a\u6b64\u53c2\u6570\u5982\u679c\u662f\u4e00\u4e2a\u5b58\u5728\u7684\u6587\u4ef6\uff0c\u5c31\u663e\u793a\u201cOK.\u201d\uff1b\u5426\u5219\u5c31\u663e\u793a”No such file.”<\/p>\n\n\n\n
\u7ec3\u4e60\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u7ed9\u811a\u672c\u4f20\u9012\u4e24\u4e2a\u53c2\u6570(\u6574\u6570)\uff1b<\/p>\n\n\n\n
\u663e\u793a\u6b64\u4e24\u8005\u4e4b\u548c\uff0c\u4e4b\u4e58\u79ef\uff1b<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
#<\/p>\n\n\n\n
if [ $# -lt 2 ]; then<\/p>\n\n\n\n
echo “Usage: cacl.sh ARG1 ARG2”<\/p>\n\n\n\n
exit 8<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
echo “The sum is: $[$1+$2].”<\/p>\n\n\n\n
echo “The prod is: $[$1*$2].”<\/p>\n\n\n\n
\u7ec3\u4e602\uff1a\u5199\u4e00\u4e2a\u811a\u672c\uff0c\u5b8c\u6210\u4ee5\u4e0b\u4efb\u52a1<\/p>\n\n\n\n
1\u3001\u4f7f\u7528\u4e00\u4e2a\u53d8\u91cf\u4fdd\u5b58\u4e00\u4e2a\u7528\u6237\u540d\uff1b<\/p>\n\n\n\n
2\u3001\u5220\u9664\u6b64\u53d8\u91cf\u4e2d\u7684\u7528\u6237\uff0c\u4e14\u4e00\u5e76\u5220\u9664\u5176\u5bb6\u76ee\u5f55\uff1b<\/p>\n\n\n\n
3\u3001\u663e\u793a\u201c\u7528\u6237\u5220\u9664\u5b8c\u6210\u201d\u7c7b\u7684\u4fe1\u606f\uff1b<\/p>\n\n\n\n
\u7ec3\u4e603\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u7ed9\u5b9a\u4e00\u4e2a\u6587\u4ef6\uff0c\u6bd4\u5982\/etc\/inittab<\/p>\n\n\n\n
\u5224\u65ad\u8fd9\u4e2a\u6587\u4ef6\u4e2d\u662f\u5426\u6709\u7a7a\u767d\u884c\uff1b<\/p>\n\n\n\n
\u5982\u679c\u6709\uff0c\u5219\u663e\u793a\u5176\u7a7a\u767d\u884c\u6570\uff1b\u5426\u5219\uff0c\u663e\u793a\u6ca1\u6709\u7a7a\u767d\u884c\u3002<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
#grep “^$” \/etc\/inittab &> \/dev\/null<\/p>\n\n\n\n
#TEST=$?<\/p>\n\n\n\n
#if [ $TEST -eq 0 ];then<\/p>\n\n\n\n
# echo `grep “^$” \/etc\/inittab | wc -l`<\/p>\n\n\n\n
#else<\/p>\n\n\n\n
# echo ” no blank lines”<\/p>\n\n\n\n
#fi<\/p>\n\n\n\n
###\u5f20\u5e05<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
#A=`grep ‘^$’ \/etc\/inittab | wc -l`<\/p>\n\n\n\n
#if [ $A -gt 0 ]; then<\/p>\n\n\n\n
# echo “$A”<\/p>\n\n\n\n
#else<\/p>\n\n\n\n
# echo “meiyoukongbaihang”<\/p>\n\n\n\n
#fi<\/p>\n\n\n\n
#\u811a\u672c\u6267\u884c\u8fc7\u7a0b\u6bd4\u8f83\u6d6a\u8d39\uff0c\u6548\u7387\u6bd4\u8f83\u4f4e\uff0c\u6240\u4ee5\u4f7f\u7528exit\u76f4\u63a5\u9000\u51fa\u811a\u672c<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
FILE=\/etc\/inittab<\/p>\n\n\n\n
if [ ! -e $FILE ]; then<\/p>\n\n\n\n
echo “No $FILE.”<\/p>\n\n\n\n
exit 8<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
if grep “^$” $FILE &> \/dev\/null; then<\/p>\n\n\n\n
echo “Total blank lines: `grep “^$” $FILE | wc -l`.”<\/p>\n\n\n\n
else<\/p>\n\n\n\n
echo “No blank line.”<\/p>\n\n\n\n
\u7ec3\u4e604\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u7ed9\u5b9a\u4e00\u4e2a\u7528\u6237\uff0c\u5224\u65ad\u5176UID\u4e0eGID\u662f\u5426\u4e00\u6837<\/p>\n\n\n\n
\u5982\u679c\u4e00\u6837\uff0c\u5c31\u663e\u793a\u6b64\u7528\u6237\u4e3a\u201cgood guy\u201d\uff1b\u5426\u5219\uff0c\u5c31\u663e\u793a\u6b64\u7528\u6237\u4e3a\u201cbad guy\u201d\u3002<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
USERNAME=user1<\/p>\n\n\n\n
USERID=`id -u $USERNAME`<\/p>\n\n\n\n
GROUPID=`id -g $USERNAME`<\/p>\n\n\n\n
if [ $USERID -eq $GROUPID ]; then<\/p>\n\n\n\n
echo “Good guy.”<\/p>\n\n\n\n
else<\/p>\n\n\n\n
echo “Bad guy.”<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
\u8fdb\u4e00\u6b65\u8981\u6c42\uff1a\u4e0d\u4f7f\u7528id\u547d\u4ee4\u83b7\u5f97\u5176id\u53f7\uff1b<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
#<\/p>\n\n\n\n
USERNAME=user1<\/p>\n\n\n\n
if ! grep “^$USERNAME\\>” \/etc\/passwd &> \/dev\/null; then<\/p>\n\n\n\n
echo “No such user: $USERNAME.”<\/p>\n\n\n\n
exit 1<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
USERID=`grep “^$USERNAME\\>” \/etc\/passwd | cut -d: -f3`<\/p>\n\n\n\n
GROUPID=`grep “^$USERNAME\\>” \/etc\/passwd | cut -d: -f4`<\/p>\n\n\n\n
if [ $USERID -eq $GROUPID ]; then<\/p>\n\n\n\n
echo “Good guy.”<\/p>\n\n\n\n
else<\/p>\n\n\n\n
echo “Bad guy.”<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
exit\uff1a\u9000\u51fa\u811a\u672c\uff08\u7528\u4e8e\u5b9a\u4e49\u6267\u884c\u72b6\u6001\u53ca\u5176\u7ed3\u679c\uff09<\/p>\n\n\n\n
exit +\u6570\u503c\uff080-255\uff090\u4e3a\u6b63\u786e\uff0c\u5176\u4ed6\u4e3a\u9519\u8bef<\/p>\n\n\n\n
\u7ec3\u4e605\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u7ed9\u5b9a\u4e00\u4e2a\u7528\u6237\uff0c\u83b7\u53d6\u5176\u5bc6\u7801\u8b66\u544a\u671f\u9650\uff1b<\/p>\n\n\n\n
\u800c\u540e\u5224\u65ad\u7528\u6237\u5bc6\u7801\u4f7f\u7528\u671f\u9650\u662f\u5426\u5df2\u7ecf\u5c0f\u4e8e\u8b66\u544a\u671f\u9650\uff1b<\/p>\n\n\n\n
\u63d0\u793a\uff1a\u8ba1\u7b97\u65b9\u6cd5\uff0c\u6700\u957f\u4f7f\u7528\u671f\u9650\u51cf\u53bb\u5df2\u7ecf\u4f7f\u7528\u7684\u5929\u6570\u5373\u4e3a\u5269\u4f59\u4f7f\u7528\u671f\u9650\uff1b<\/p>\n\n\n\n
\u5982\u679c\u5c0f\u4e8e\uff0c\u5219\u663e\u793a\u201cWarning\u201d\uff1b\u5426\u5219\uff0c\u5c31\u663e\u793a\u201cOK\u201d\u3002<\/p>\n\n\n\n
\u5706\u6574\uff1a\u4e22\u5f03\u5c0f\u6570\u70b9\u540e\u7684\u6240\u6709\u5185\u5bb9\uff08bash\u9ed8\u8ba4\u4f7f\u7528\u6b64\u79cd\u65b9\u5f0f\u8fdb\u884c\u8ba1\u7b97\uff09<\/p>\n\n\n\n
#!\/bin\/bash<\/p>\n\n\n\n
W=`grep “student” \/etc\/shadow | cut -d: -f6`<\/p>\n\n\n\n
S=`date +%s`<\/p>\n\n\n\n
T=`expr $S\/86400`<\/p>\n\n\n\n
L=`grep “^student” \/etc\/shadow | cut -d: -f5`<\/p>\n\n\n\n
N=`grep “^student” \/etc\/shadow | cut -d: -f3`<\/p>\n\n\n\n
SY=$[$L-$[$T-$N]]<\/p>\n\n\n\n
if [ $SY -lt $W ]; then<\/p>\n\n\n\n
echo ‘Warning’<\/p>\n\n\n\n
else<\/p>\n\n\n\n
echo ‘OK’<\/p>\n\n\n\n
fi<\/p>\n\n\n\n
\u7ec3\u4e606\uff1a\u5199\u4e00\u4e2a\u811a\u672c<\/p>\n\n\n\n
\u5224\u5b9a\u547d\u4ee4\u5386\u53f2\u4e2d\u5386\u53f2\u547d\u4ee4\u7684\u603b\u6761\u76ee\u662f\u5426\u5927\u4e8e1000\uff1b\u5982\u679c\u5927\u4e8e\uff0c\u5219\u663e\u793a\u201cSome command will gone.\u201d\uff1b\u5426\u5219\u663e\u793a\u201cOK\u201d\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
16.1 \u7b97\u672f\u8fd0\u7b97\u65b9\u6cd5 shell\u4e2d\u5982\u4f55\u8fdb\u884c\u7b97\u672f\u8fd0\u7b97\uff1a A=3 B=6 1\u3001let \u7b97\u672f\u8fd0\u7b97\u8868\u8fbe\u5f0f […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-493","post","type-post","status-publish","format-standard","hentry","category-linux"],"aioseo_notices":[],"views":218,"_links":{"self":[{"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/posts\/493","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=493"}],"version-history":[{"count":1,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/posts\/493\/revisions"}],"predecessor-version":[{"id":494,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=\/wp\/v2\/posts\/493\/revisions\/494"}],"wp:attachment":[{"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=493"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=493"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceansource.cc\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}