將文件視為集合併對其執行集合操作的 Linux 工具

有誰知道專門設計用於將文件視為集合併對其執行集合操作的任何 linux 工具？像差異，交叉點等？

假設元素是除 NUL 和換行符以外的字元串（但請注意，換行符在文件名中有效），您可以將集合表示為每行一個元素的文本文件，並使用一些標準的 Unix 實用程序。

設置會員資格

$ grep -Fxc 'element' set   # outputs 1 if element is in set
                           # outputs >1 if set is a multi-set
                           # outputs 0 if element is not in set

$ grep -Fxq 'element' set   # returns 0 (true)  if element is in set
                           # returns 1 (false) if element is not in set

$ awk '$0 == "element" { s=1; exit }; END { exit !s }' set
# returns 0 if element is in set, 1 otherwise.

$ awk -v e='element' '$0 == e { s=1; exit } END { exit !s }'

設置交點

$ comm -12 <(sort set1) <(sort set2)  # outputs intersect of set1 and set2

$ grep -xF -f set1 set2

$ sort set1 set2 | uniq -d

$ join -t <(sort A) <(sort B)

$ awk '!done { a[$0]; next }; $0 in a' set1 done=1 set2

設置平等

$ cmp -s <(sort set1) <(sort set2) # returns 0 if set1 is equal to set2
                                  # returns 1 if set1 != set2

$ cmp -s <(sort -u set1) <(sort -u set2)
# collapses multi-sets into sets and does the same as previous

$ awk '{ if (!($0 in a)) c++; a[$0] }; END{ exit !(c==NR/2) }' set1 set2
# returns 0 if set1 == set2
# returns 1 if set1 != set2

$ awk '{ a[$0] }; END{ exit !(length(a)==NR/2) }' set1 set2
# same as previous, requires >= gnu awk 3.1.5

設置基數

$ wc -l < set     # outputs number of elements in set

$ awk 'END { print NR }' set

$ sed '$=' set

子集測試

$ comm -23 <(sort -u subset) <(sort -u set) | grep -q '^'
# returns true iff subset is not a subset of set (has elements not in set)

$ awk '!done { a[$0]; next }; { if !($0 in a) exit 1 }' set done=1 subset
# returns 0 if subset is a subset of set
# returns 1 if subset is not a subset of set

設置聯合

$ cat set1 set2     # outputs union of set1 and set2
                   # assumes they are disjoint

$ awk 1 set1 set2   # ditto

$ cat set1 set2 ... setn   # union over n sets

$ sort -u set1 set2  # same, but doesn't assume they are disjoint

$ sort set1 set2 | uniq

$ awk '!a[$0]++' set1 set2       # ditto without sorting

設置補碼

$ comm -23 <(sort set1) <(sort set2)
# outputs elements in set1 that are not in set2

$ grep -vxF -f set2 set1           # ditto

$ sort set2 set2 set1 | uniq -u    # ditto

$ awk '!done { a[$0]; next }; !($0 in a)' set2 done=1 set1

設置對稱差

$ comm -3 <(sort set1) <(sort set2) | tr -d '\t'  # assumes not tab in sets
# outputs elements that are in set1 or in set2 but not both

$ sort set1 set2 | uniq -u

$ cat <(grep -vxF -f set1 set2) <(grep -vxF -f set2 set1)

$ grep -vxF -f set1 set2; grep -vxF -f set2 set1

$ awk '!done { a[$0]; next }; $0 in a { delete a[$0]; next }; 1;
      END { for (b in a) print b }' set1 done=1 set2

電源組

一組顯示空間的所有可能子集分隔，每行一個：

$ p() { [ "$#" -eq 0 ] && echo || (shift; p "$@") |
       while read r; do printf '%s %s\n%s\n' "$1" "$r" "$r"; done; }
$ p $(cat set)

（假設元素不包含 SPC、TAB（假設預設值為$IFS）、反斜杠、萬用字元）。

設置笛卡爾積

$ while IFS= read -r a; do while IFS= read -r b; do echo "$a, $b"; done < set1; done < set2

$ awk '!done { a[$0]; next }; { for (i in a) print i, $0 }' set1 done=1 set2

不相交集測試

$ comm -12 <(sort set1) <(sort set2)  # does not output anything if disjoint

$ awk '++seen[$0] == 2 { exit 1 }' set1 set2 # returns 0 if disjoint
                                            # returns 1 if not

空集測試

$ wc -l < set            # outputs 0  if the set is empty
                        # outputs >0 if the set is not empty

$ grep -q '^' set        # returns true (0 exit status) unless set is empty

$ awk '{ exit 1 }' set   # returns true (0 exit status) if set is empty

最低限度

$ sort set | head -n 1   # outputs the minimum (lexically) element in the set

$ awk 'NR == 1 { min = $0 }; $0 < min { min = $0 }; END { print min }'
# ditto, but does numeric comparison when elements are numerical

最大

$ sort test | tail -n 1    # outputs the maximum element in the set

$ sort -r test | head -n 1

$ awk '$0 > max { max = $0 }; END { print max }'
# ditto, but does numeric comparison when elements are numerical

全部可在http://www.catonmat.net/blog/set-operations-in-unix-shell-simplified/

引用自：https://unix.stackexchange.com/questions/11343