{"id":92,"date":"2025-06-24T09:59:46","date_gmt":"2025-06-24T01:59:46","guid":{"rendered":"http:\/\/1.14.207.80\/?p=92"},"modified":"2025-06-24T11:13:19","modified_gmt":"2025-06-24T03:13:19","slug":"linux%e5%9f%ba%e7%a1%80%ef%bc%88shell%e8%84%9a%e6%9c%ac%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.zhangjianjia.xyz\/index.php\/2025\/06\/24\/linux%e5%9f%ba%e7%a1%80%ef%bc%88shell%e8%84%9a%e6%9c%ac%ef%bc%89\/","title":{"rendered":"Linux\u57fa\u7840\uff08shell\u811a\u672c\uff09"},"content":{"rendered":"\n

Shell\u811a\u672c\u7f16\u7a0b\u5b8c\u5168\u6307\u5357<\/h1>\n

\u4e00\u3001\u57fa\u7840\u7ed3\u6784<\/h2>\n

1. \u811a\u672c\u683c\u5f0f<\/h3>\n
#!\/usr\/bin\/env bash  # Shebang\u884c\uff08\u63a8\u8350\u53ef\u79fb\u690d\u5199\u6cd5\uff09\n# \u5355\u884c\u6ce8\u91ca\n: <<'COMMENT'\n\u591a\u884c\u6ce8\u91ca\u793a\u4f8b\n\u652f\u6301\u6362\u884c\u6587\u672c\nCOMMENT\n<\/code><\/pre>\n
2. \u6267\u884c\u65b9\u5f0f<\/h3>\n\n\n\n\n\n\n\n\n
\u65b9\u6cd5<\/strong><\/th>\n\u547d\u4ee4<\/strong><\/th>\n\u8bf4\u660e<\/strong><\/th>\n<\/tr>\n<\/thead>\n
\u6dfb\u52a0\u6267\u884c\u6743\u9650<\/td>\nchmod +x script.sh<\/code><\/td>\n\u4f7f\u811a\u672c\u53ef\u6267\u884c<\/td>\n<\/tr>\n
\u76f4\u63a5\u6267\u884c<\/td>\n.\/script.sh<\/code><\/td>\n\u9700\u6267\u884c\u6743\u9650<\/td>\n<\/tr>\n
\u89e3\u91ca\u5668\u6267\u884c<\/td>\nbash script.sh<\/code><\/td>\n\u65e0\u9700\u6267\u884c\u6743\u9650<\/td>\n<\/tr>\n
\u73af\u5883\u53d8\u91cf\u6267\u884c<\/td>\nscript.sh<\/code><\/td>\n\u9700\u8f6f\u94fe\u63a5\u5230$PATH<\/code>\u76ee\u5f55<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\u8c03\u8bd5\u5de5\u5177\uff1a<\/strong><\/p>\n
    \n
  • bash -n script.sh<\/code>\uff1a\u8bed\u6cd5\u68c0\u67e5<\/li>\n
  • bash -x script.sh<\/code>\uff1a\u9010\u884c\u8c03\u8bd5\uff08\u663e\u793a\u6267\u884c\u8fc7\u7a0b\uff09<\/li>\n<\/ul>\n
    \u4e8c\u3001\u53d8\u91cf\u5904\u7406<\/h2>\n
    1. \u53d8\u91cf\u7c7b\u578b<\/h3>\n\n\n\n\n\n\n\n
    \u7c7b\u578b<\/strong><\/th>\n\u5b9a\u4e49\u65b9\u5f0f<\/strong><\/th>\n\u793a\u4f8b<\/strong><\/th>\n\u67e5\u770b\u547d\u4ee4<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    \u666e\u901a\u53d8\u91cf<\/td>\nvar="value"<\/code><\/td>\nuser="alice"<\/code><\/td>\necho $user<\/code><\/td>\n<\/tr>\n
    \u73af\u5883\u53d8\u91cf<\/td>\nexport var="value"<\/code><\/td>\nexport PATH=$PATH:\/add<\/code><\/td>\nenv<\/code><\/td>\n<\/tr>\n
    \u53ea\u8bfb\u5e38\u91cf<\/td>\nreadonly var="value"<\/code><\/td>\nreadonly VERSION=1.0<\/code><\/td>\nreadonly<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    2. \u53d8\u91cf\u64cd\u4f5c<\/h3>\n
    name="Bob"\necho ${name}          # \u6807\u51c6\u5f15\u7528\uff08\u63a8\u8350\uff09\nname+=" Smith"        # \u8ffd\u52a0 \u2192 "Bob Smith"\nunset name            # \u5220\u9664\u53d8\u91cf\n<\/code><\/pre>\n
    3. \u6838\u5fc3\u5185\u7f6e\u53d8\u91cf<\/h3>\n\n\n\n\n\n\n\n\n
    \u53d8\u91cf<\/strong><\/th>\n\u542b\u4e49<\/strong><\/th>\n\u53d8\u91cf<\/strong><\/th>\n\u542b\u4e49<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    $PATH<\/code><\/td>\n\u547d\u4ee4\u641c\u7d22\u8def\u5f84<\/td>\n$?<\/code><\/td>\n\u4e0a\u6761\u547d\u4ee4\u9000\u51fa\u72b6\u6001<\/td>\n<\/tr>\n
    $UID<\/code><\/td>\n\u7528\u6237ID<\/td>\n$$<\/code><\/td>\n\u5f53\u524d\u8fdb\u7a0bPID<\/td>\n<\/tr>\n
    $HOSTNAME<\/code><\/td>\n\u4e3b\u673a\u540d<\/td>\n$PPID<\/code><\/td>\n\u7236\u8fdb\u7a0bPID<\/td>\n<\/tr>\n
    $HISTSIZE<\/code><\/td>\n\u5386\u53f2\u8bb0\u5f55\u6761\u6570<\/td>\n$RANDOM<\/code><\/td>\n\u968f\u673a\u6570(0-32767)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    \u4e09\u3001\u6570\u636e\u8fd0\u7b97<\/h2>\n
    1. \u7b97\u672f\u8fd0\u7b97<\/h3>\n
    let result="10 + 5"         # let\u8ba1\u7b97\nresult=$((10 * 2))          # $(( ))\u8ba1\u7b97\nresult=$(expr 10 - 3)       # expr\u547d\u4ee4\n\n# \u589e\u5f3a\u8d4b\u503c\ncount=5\n((count *= 3))              # count=15\n((count--))                 # count=14\n<\/code><\/pre>\n
    2. \u6d6e\u70b9\u6570\u8ba1\u7b97<\/h3>\n
    pi=3.1415926\nprintf "%.2f\\n" $pi         # 3.14 (\u4fdd\u7559\u4e24\u4f4d\u5c0f\u6570)\nresult=$(echo "scale=2; 10\/3" | bc)  # 3.33 (bc\u8ba1\u7b97\u5668)\n<\/code><\/pre>\n
    3. \u968f\u673a\u6570\u751f\u6210<\/h3>\n
    echo $((RANDOM % 100))      # 0-99\u968f\u673a\u6570\necho $((RANDOM % 50 + 1))   # 1-50\u968f\u673a\u6570\n<\/code><\/pre>\n
    \u56db\u3001\u6761\u4ef6\u6d4b\u8bd5<\/h2>\n
    1. \u6d4b\u8bd5\u8bed\u6cd5<\/h3>\n
    test -f file.txt       # \u4f20\u7edf\u5199\u6cd5\n[ -d "\/data" ]         # \u5e38\u7528\u5199\u6cd5\uff08\u6ce8\u610f\u7a7a\u683c\uff09\n[[ $str =~ ^[A-Z] ]]   # \u6b63\u5219\u5339\u914d\uff08\u9ad8\u7ea7\u6a21\u5f0f\uff09\n<\/code><\/pre>\n
    2. \u6d4b\u8bd5\u9009\u9879\u901f\u67e5<\/h3>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
    \u7c7b\u578b<\/strong><\/th>\n\u9009\u9879<\/strong><\/th>\n\u542b\u4e49<\/strong><\/th>\n\u793a\u4f8b<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    \u6587\u4ef6\u6d4b\u8bd5<\/strong><\/td>\n-e<\/code><\/td>\n\u6587\u4ef6\u662f\u5426\u5b58\u5728<\/td>\n[ -e "file" ]<\/code><\/td>\n<\/tr>\n
    <\/td>\n-f<\/code><\/td>\n\u662f\u5426\u4e3a\u666e\u901a\u6587\u4ef6<\/td>\n[ -f "\/path" ]<\/code><\/td>\n<\/tr>\n
    <\/td>\n-x<\/code><\/td>\n\u662f\u5426\u53ef\u6267\u884c<\/td>\n[ -x "\/bin\/ls" ]<\/code><\/td>\n<\/tr>\n
    \u5b57\u7b26\u4e32<\/strong><\/td>\n-z<\/code><\/td>\n\u5b57\u7b26\u4e32\u4e3a\u7a7a<\/td>\n[ -z "$var" ]<\/code><\/td>\n<\/tr>\n
    <\/td>\n==<\/code><\/td>\n\u5b57\u7b26\u4e32\u76f8\u7b49<\/td>\n[[ "$s1" == "$s2" ]]<\/code><\/td>\n<\/tr>\n
    \u6570\u503c\u6bd4\u8f83<\/strong><\/td>\n-eq<\/code><\/td>\n\u7b49\u4e8e<\/td>\n[ $n1 -eq 10 ]<\/code><\/td>\n<\/tr>\n
    <\/td>\n-gt<\/code><\/td>\n\u5927\u4e8e<\/td>\n[ $n1 -gt $n2 ]<\/code><\/td>\n<\/tr>\n
    \u903b\u8f91\u7ec4\u5408<\/strong><\/td>\n&&<\/code><\/td>\n\u4e0e (AND)<\/td>\n[ cond1 ] && [ cond2 ]<\/code><\/td>\n<\/tr>\n
    <\/td>\n`<\/td>\n<\/td>\n`<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    \u4e94\u3001\u6d41\u7a0b\u63a7\u5236<\/h2>\n
    1. \u6761\u4ef6\u5206\u652f<\/h3>\n
    if\u8bed\u53e5<\/strong><\/p>\n
    if [[ $age -ge 18 ]]; then\n   echo "\u6210\u5e74\u4eba"\nelif [[ $age -ge 13 ]]; then\n   echo "\u9752\u5c11\u5e74"\nelse\n   echo "\u513f\u7ae5"\nfi\n<\/code><\/pre>\n
    case\u8bed\u53e5<\/strong><\/p>\n
    case $OS in\n  Linux)\n    echo "\u4f7f\u7528 apt\/yum"\n    ;;\n  Darwin)\n    echo "\u4f7f\u7528 brew"\n    ;;\n  *)\n    echo "\u672a\u77e5\u7cfb\u7edf: $OS"\n    exit 1\n    ;;\nesac\n<\/code><\/pre>\n
    2. \u5faa\u73af\u7ed3\u6784<\/h3>\n
    for\u5faa\u73af<\/strong><\/p>\n
    # \u5217\u8868\u904d\u5386\nfor file in *.log; do\n   gzip "$file"\ndone\n\n# C\u8bed\u8a00\u98ce\u683c\nfor ((i=0; i<10; i+=2)); do\n   echo "\u5076\u6570: $i"\ndone\n\n# \u6570\u5b57\u5e8f\u5217\nfor i in $(seq 5); do\n   echo "\u8ba1\u6570: $i"\ndone\n<\/code><\/pre>\n
    while\/until\u5faa\u73af<\/strong><\/p>\n
    # while\uff1a\u6761\u4ef6\u4e3a\u771f\u6267\u884c\ncount=1\nwhile [[ $count -le 5 ]]; do\n   echo "While: $count"\n   ((count++))\ndone\n\n# until\uff1a\u6761\u4ef6\u4e3a\u5047\u6267\u884c\nuntil [[ $count -gt 10 ]]; do\n   echo "Until: $count"\n   ((count++))\ndone\n<\/code><\/pre>\n
    \u516d\u3001\u51fd\u6570\u4e0e\u8f93\u5165\u8f93\u51fa<\/h2>\n
    1. \u51fd\u6570\u5b9a\u4e49<\/h3>\n
    # \u5b9a\u4e49\u51fd\u6570\ndisk_usage() {\n  local threshold=80  # \u5c40\u90e8\u53d8\u91cf\n  usage=$(df -h \/ | awk 'NR==2 {print $5}' | tr -d '%')\n  \n  if ((usage > threshold)); then\n    echo "\u8b66\u544a: \u78c1\u76d8\u4f7f\u7528\u7387 ${usage}% > ${threshold}%"\n    return 1\n  fi\n  return 0\n}\n\n# \u8c03\u7528\u51fd\u6570\ndisk_usage\n<\/code><\/pre>\n
    2. \u7528\u6237\u8f93\u5165<\/h3>\n
    read -t 15 -p "\u7528\u6237\u540d: " username  # -t\uff1a\u8d85\u65f6(\u79d2)\nread -s -p "\u5bc6\u7801: " passwd        # -s\uff1a\u9690\u85cf\u8f93\u5165\n\n# \u591a\u53d8\u91cf\u8bfb\u53d6\nread first last <<< "John Doe"\n<\/code><\/pre>\n
    3. \u8f93\u5165\u8f93\u51fa\u91cd\u5b9a\u5411<\/h3>\n
    cmd > file      # \u6807\u51c6\u8f93\u51fa\u91cd\u5b9a\u5411\uff08\u8986\u76d6\uff09\ncmd >> file     # \u6807\u51c6\u8f93\u51fa\u91cd\u5b9a\u5411\uff08\u8ffd\u52a0\uff09\ncmd 2> file     # \u9519\u8bef\u8f93\u51fa\u91cd\u5b9a\u5411\ncmd &> file     # \u6240\u6709\u8f93\u51fa\u91cd\u5b9a\u5411\n\n# \u7ba1\u9053\u9ad8\u7ea7\u7528\u6cd5\necho "data" | {\n  read input\n  process "$input"\n  echo "\u7ed3\u679c: $result"\n}\n<\/code><\/pre>\n
    \u4e03\u3001Shell\u914d\u7f6e\u6587\u4ef6<\/h2>\n
    1. \u914d\u7f6e\u6587\u4ef6\u5206\u7c7b<\/h3>\n\n\n\n\n\n\n\n\n
    \u6587\u4ef6<\/strong><\/th>\n\u4f5c\u7528\u8303\u56f4<\/strong><\/th>\n\u52a0\u8f7d\u65f6\u673a<\/strong><\/th>\n\u4e3b\u8981\u7528\u9014<\/strong><\/th>\n<\/tr>\n<\/thead>\n
    \/etc\/profile<\/code><\/td>\n\u5168\u5c40<\/td>\n\u767b\u5f55Shell<\/td>\n\u7cfb\u7edf\u73af\u5883\u53d8\u91cf\u3001\u542f\u52a8\u7a0b\u5e8f<\/td>\n<\/tr>\n
    \/etc\/bashrc<\/code><\/td>\n\u5168\u5c40<\/td>\n\u4ea4\u4e92\u5f0f\u975e\u767b\u5f55Shell<\/td>\n\u5168\u5c40\u522b\u540d\u3001\u51fd\u6570\u5b9a\u4e49<\/td>\n<\/tr>\n
    ~\/.bash_profile<\/code><\/td>\n\u7528\u6237<\/td>\n\u767b\u5f55Shell<\/td>\n\u7528\u6237\u73af\u5883\u53d8\u91cf\u3001\u4e2a\u4eba\u521d\u59cb\u5316<\/td>\n<\/tr>\n
    ~\/.bashrc<\/code><\/td>\n\u7528\u6237<\/td>\n\u4ea4\u4e92\u5f0fShell<\/td>\n\u7528\u6237\u522b\u540d\u3001\u51fd\u6570\u3001\u63d0\u793a\u7b26\u8bbe\u7f6e<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    2. \u52a0\u8f7d\u987a\u5e8f<\/h3>\n
    \u767b\u5f55Shell\uff1a\n  \/etc\/profile \u2192 ~\/.bash_profile \u2192 ~\/.bashrc \u2192 \/etc\/bashrc\n\n\u975e\u767b\u5f55\u4ea4\u4e92\u5f0fShell\uff1a\n  ~\/.bashrc \u2192 \/etc\/bashrc\n<\/code><\/pre>\n
    \u516b\u3001\u9ad8\u7ea7\u6280\u5de7<\/h2>\n
    1. \u53d8\u91cf\u64cd\u4f5c<\/h3>\n
    \u4f4d\u7f6e\u53d8\u91cf<\/strong><\/p>\n
    #!\/bin\/bash\necho "\u811a\u672c\u540d: $0"\necho "\u7b2c\u4e00\u4e2a\u53c2\u6570: $1"\necho "\u6240\u6709\u53c2\u6570: $@"\necho "\u53c2\u6570\u4e2a\u6570: $#"\n<\/code><\/pre>\n
    \u5f02\u6216\u4ea4\u6362<\/strong><\/p>\n
    a=10; b=20\na=$((a^b)); b=$((a^b)); a=$((a^b))\necho "a=$a, b=$b"  # a=20, b=10\n<\/code><\/pre>\n
    2. \u5b89\u5168\u811a\u672c<\/h3>\n
    #!\/usr\/bin\/env bash\nset -e    # \u547d\u4ee4\u5931\u8d25\u7acb\u5373\u9000\u51fa\nset -u    # \u4f7f\u7528\u672a\u5b9a\u4e49\u53d8\u91cf\u65f6\u62a5\u9519\nset -o pipefail  # \u7ba1\u9053\u4e2d\u4efb\u610f\u547d\u4ee4\u5931\u8d25\u5219\u6574\u4f53\u5931\u8d25\n\n# \u5b89\u5168\u5220\u9664\u793a\u4f8b\nreadonly BACKUP_DIR="\/backups"\n[[ -d "$BACKUP_DIR" ]] || exit 1\nrm -rf "$BACKUP_DIR"\/*\n<\/code><\/pre>\n
    3. \u5b50\u8fdb\u7a0b\u63a7\u5236<\/h3>\n
    # () \u521b\u5efa\u5b50\u8fdb\u7a0b\uff08\u53d8\u91cf\u9694\u79bb\uff09\n(var=100; echo "\u5b50\u8fdb\u7a0b: $var")  # \u8f93\u51fa100\necho "\u7236\u8fdb\u7a0b: $var"            # \u7a7a\u503c\n\n# {} \u5f53\u524d\u8fdb\u7a0b\u6267\u884c\uff08\u5171\u4eab\u53d8\u91cf\uff09\n{ var=200; echo "\u5f53\u524d\u8fdb\u7a0b: $var"; }  # 200\necho "\u5f53\u524d\u8fdb\u7a0b: $var"               # 200\n<\/code><\/pre>\n
    4. \u5b9e\u7528\u4ee3\u7801\u7247\u6bb5<\/h3>\n
    \u8fdb\u5ea6\u6761\u663e\u793a<\/strong><\/p>\n
    for i in {1..20}; do\n  printf "\\r[%-20s] %d%%" $(printf "%${i}s" | tr ' ' '#') $((i*5))\n  sleep 0.1\ndone\necho\n<\/code><\/pre>\n
    \u6d6e\u70b9\u6570\u6bd4\u8f83<\/strong><\/p>\n
    compare_floats() {\n  result=$(echo "$1 > $2" | bc)\n  [[ $result -eq 1 ]] && echo "$1 > $2" || echo "$1 <= $2"\n}\n\ncompare_floats 3.14 2.71  # 3.14 > 2.71\n<\/code><\/pre>\n
    \u4e5d\u3001\u6700\u4f73\u5b9e\u8df5<\/h2>\n
      \n
    1. \u53d8\u91cf\u5f15\u7528<\/strong>\uff1a\u59cb\u7ec8\u7528${var}<\/code>\u66ff\u4ee3$var<\/code><\/li>\n
    2. \u9519\u8bef\u5904\u7406<\/strong>\uff1a\u5173\u952e\u64cd\u4f5c\u68c0\u67e5\u9000\u51fa\u7801 if ! cmd; then...<\/code><\/li>\n
    3. \u8def\u5f84\u5904\u7406<\/strong>\uff1a\u4f7f\u7528\u7edd\u5bf9\u8def\u5f84\uff0c\u907f\u514d\u4f9d\u8d56\u5f53\u524d\u76ee\u5f55<\/li>\n
    4. \u517c\u5bb9\u6027<\/strong>\uff1a\u91cd\u8981\u811a\u672c\u58f0\u660eShell\u7248\u672c #!\/usr\/bin\/env bash<\/code><\/li>\n
    5. \u8c03\u8bd5<\/strong>\uff1a\u590d\u6742\u811a\u672c\u4f7f\u7528 set -x<\/code> \u8c03\u8bd5\u6a21\u5f0f<\/li>\n<\/ol>\n
      \n
      \u901a\u8fc7 bash -n script.sh<\/code> \u8fdb\u884c\u9759\u6001\u68c0\u67e5\uff0cshellcheck<\/code> \u5de5\u5177\u53ef\u63d0\u4f9b\u66f4\u4e13\u4e1a\u7684\u68c0\u67e5<\/p>\n<\/blockquote>\n<\/div>\n\n\n\n
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