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awk [2024/07/19 00:42]
admin angelegt 		awk [2025/05/05 14:06] (aktuell)
admin
Zeile 1: Zeile 1:
 +awk ist eine leistungsstarke Textverarbeitungswerkzeug in Unix ähnlichen Betriebssystemen. Es ermöglicht das Extrahieren und Verarbeiten von Daten in Textdateien.
  
 +=====Syntax=====
 +
 +<code>
 +awk 'pattern { action }' file
 +</code>
 +
 +  * pattern: Eine Bedingung, die überprüft wird. Wenn sie wahr ist, wird die Aktion ausgeführt.
 +  * action: Eine Aktion, die ausgeführt wird, wenn das Muster erfüllt ist.
 +  * file: Die Eingabedatei, die verarbeitet wird.
 +
 +See also [[grep]], [[sed|sed]].
 +
 +Angenommen, du hast eine Datei namens example.txt mit folgendem Inhalt:
 +
 +<code>
 +Apfel 10
 +Banane 5
 +Kirsche 20
 +</code>
 +
 +Ein paar Beispiele:
 +<code>
 +# Jede Zeile einfach ausgeben
 +awk '{print}' example.txt
 +
 +# 1. Spalte jeder Zeile ausgeben
 +awk '{print $1}' example.txt
 +
 +# Bedingungen (wenn die 2. Spalte größer als 5 ist)
 +awk '$2 > 5 {print}' example.txt
 +
 +# Berechnungen (2. Spalte jeder Zeile zu "sum" hinzufügen und am Ende die Summe ausgeben)
 +awk '{sum += $2} END {print "Summe: " sum}' example.txt
 +
 +# Regular esxpressions
 +awk '/Apfel/ {print}' example.txt
 +
 +# Multiline Kommentare (/**/) entfernen
 +awk '!in_comment && /\/\*/ {in_comment=1; next} in_comment && /\*\// {in_comment=0; next} !in_comment'
 +</code>
 +
 +=====CheatSheet=====
 +
 +<code>
 +FILE SPACING:
 +
 + # double space a file
 + awk '1;{print ""}'
 + awk 'BEGIN{ORS="\n\n"};1'
 +
 + # double space a file which already has blank lines in it. Output file
 + # should contain no more than one blank line between lines of text.
 + # NOTE: On Unix systems, DOS lines which have only CRLF (\r\n) are
 + # often treated as non-blank, and thus 'NF' alone will return TRUE.
 + awk 'NF{print $0 "\n"}'
 +
 + # triple space a file
 + awk '1;{print "\n"}'
 +
 +NUMBERING AND CALCULATIONS:
 +
 + # precede each line by its line number FOR THAT FILE (left alignment).
 + # Using a tab (\t) instead of space will preserve margins.
 + awk '{print FNR "\t" $0}' files*
 +
 + # precede each line by its line number FOR ALL FILES TOGETHER, with tab.
 + awk '{print NR "\t" $0}' files*
 +
 + # number each line of a file (number on left, right-aligned)
 + # Double the percent signs if typing from the DOS command prompt.
 + awk '{printf("%5d : %s\n", NR,$0)}'
 +
 + # number each line of file, but only print numbers if line is not blank
 + # Remember caveats about Unix treatment of \r (mentioned above)
 + awk 'NF{$0=++a " :" $0};1'
 + awk '{print (NF? ++a " :" :"") $0}'
 +
 + # count lines (emulates "wc -l")
 + awk 'END{print NR}'
 +
 + # print the sums of the fields of every line
 + awk '{s=0; for (i=1; i<=NF; i++) s=s+$i; print s}'
 +
 + # add all fields in all lines and print the sum
 + awk '{for (i=1; i<=NF; i++) s=s+$i}; END{print s}'
 +
 + # print every line after replacing each field with its absolute value
 + awk '{for (i=1; i<=NF; i++) if ($i < 0) $i = -$i; print }'
 + awk '{for (i=1; i<=NF; i++) $i = ($i < 0) ? -$i : $i; print }'
 +
 + # print the total number of fields ("words") in all lines
 + awk '{ total = total + NF }; END {print total}' file
 +
 + # print the total number of lines that contain "Beth"
 + awk '/Beth/{n++}; END {print n+0}' file
 +
 + # print the largest first field and the line that contains it
 + # Intended for finding the longest string in field #1
 + awk '$1 > max {max=$1; maxline=$0}; END{ print max, maxline}'
 +
 + # print the number of fields in each line, followed by the line
 + awk '{ print NF ":" $0 } '
 +
 + # print the last field of each line
 + awk '{ print $NF }'
 +
 + # print the last field of the last line
 + awk '{ field = $NF }; END{ print field }'
 +
 + # print every line with more than 4 fields
 + awk 'NF > 4'
 +
 + # print every line where the value of the last field is > 4
 + awk '$NF > 4'
 +
 +STRING CREATION:
 +
 + # create a string of a specific length (e.g., generate 513 spaces)
 + awk 'BEGIN{while (a++<513) s=s " "; print s}'
 +
 + # insert a string of specific length at a certain character position
 + # Example: insert 49 spaces after column #6 of each input line.
 + gawk --re-interval 'BEGIN{while(a++<49)s=s " "};{sub(/^.{6}/,"&" s)};1'
 +
 +ARRAY CREATION:
 +
 + # These next 2 entries are not one-line scripts, but the technique
 + # is so handy that it merits inclusion here.
 + 
 + # create an array named "month", indexed by numbers, so that month[1]
 + # is 'Jan', month[2] is 'Feb', month[3] is 'Mar' and so on.
 + split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec", month, " ")
 +
 + # create an array named "mdigit", indexed by strings, so that
 + # mdigit["Jan"] is 1, mdigit["Feb"] is 2, etc. Requires "month" array
 + for (i=1; i<=12; i++) mdigit[month[i]] = i
 +
 +TEXT CONVERSION AND SUBSTITUTION:
 +
 + # IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format
 + awk '{sub(/\r$/,"")};1'   # assumes EACH line ends with Ctrl-M
 +
 + # IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format
 + awk '{sub(/$/,"\r")};1'
 +
 + # IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format
 + awk 1
 +
 + # IN DOS ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format
 + # Cannot be done with DOS versions of awk, other than gawk:
 + gawk -v BINMODE="w" '1' infile >outfile
 +
 + # Use "tr" instead.
 + tr -d \r <infile >outfile            # GNU tr version 1.22 or higher
 +
 + # delete leading whitespace (spaces, tabs) from front of each line
 + # aligns all text flush left
 + awk '{sub(/^[ \t]+/, "")};1'
 +
 + # delete trailing whitespace (spaces, tabs) from end of each line
 + awk '{sub(/[ \t]+$/, "")};1'
 +
 + # delete BOTH leading and trailing whitespace from each line
 + awk '{gsub(/^[ \t]+|[ \t]+$/,"")};1'
 + awk '{$1=$1};1'           # also removes extra space between fields
 +
 + # insert 5 blank spaces at beginning of each line (make page offset)
 + awk '{sub(/^/, "     ")};1'
 +
 + # align all text flush right on a 79-column width
 + awk '{printf "%79s\n", $0}' file*
 +
 + # center all text on a 79-character width
 + awk '{l=length();s=int((79-l)/2); printf "%"(s+l)"s\n",$0}' file*
 +
 + # substitute (find and replace) "foo" with "bar" on each line
 + awk '{sub(/foo/,"bar")}; 1'           # replace only 1st instance
 + gawk '{$0=gensub(/foo/,"bar",4)}; 1'  # replace only 4th instance
 + awk '{gsub(/foo/,"bar")}; 1'          # replace ALL instances in a line
 +
 + # substitute "foo" with "bar" ONLY for lines which contain "baz"
 + awk '/baz/{gsub(/foo/, "bar")}; 1'
 +
 + # substitute "foo" with "bar" EXCEPT for lines which contain "baz"
 + awk '!/baz/{gsub(/foo/, "bar")}; 1'
 +
 + # change "scarlet" or "ruby" or "puce" to "red"
 + awk '{gsub(/scarlet|ruby|puce/, "red")}; 1'
 +
 + # reverse order of lines (emulates "tac")
 + awk '{a[i++]=$0} END {for (j=i-1; j>=0;) print a[j--] }' file*
 +
 + # if a line ends with a backslash, append the next line to it (fails if
 + # there are multiple lines ending with backslash...)
 + awk '/\\$/ {sub(/\\$/,""); getline t; print $0 t; next}; 1' file*
 +
 + # print and sort the login names of all users
 + awk -F ":" '{print $1 | "sort" }' /etc/passwd
 +
 + # print the first 2 fields, in opposite order, of every line
 + awk '{print $2, $1}' file
 +
 + # switch the first 2 fields of every line
 + awk '{temp = $1; $1 = $2; $2 = temp}' file
 +
 + # print every line, deleting the second field of that line
 + awk '{ $2 = ""; print }'
 +
 + # print in reverse order the fields of every line
 + awk '{for (i=NF; i>0; i--) printf("%s ",$i);print ""}' file
 +
 + # concatenate every 5 lines of input, using a comma separator
 + # between fields
 + awk 'ORS=NR%5?",":"\n"' file
 +
 +SELECTIVE PRINTING OF CERTAIN LINES:
 +
 + # print first 10 lines of file (emulates behavior of "head")
 + awk 'NR < 11'
 +
 + # print first line of file (emulates "head -1")
 + awk 'NR>1{exit};1'
 +
 +  # print the last 2 lines of a file (emulates "tail -2")
 + awk '{y=x "\n" $0; x=$0};END{print y}'
 +
 + # print the last line of a file (emulates "tail -1")
 + awk 'END{print}'
 +
 + # print only lines which match regular expression (emulates "grep")
 + awk '/regex/'
 +
 + # print only lines which do NOT match regex (emulates "grep -v")
 + awk '!/regex/'
 +
 + # print any line where field #5 is equal to "abc123"
 + awk '$5 == "abc123"'
 +
 + # print only those lines where field #5 is NOT equal to "abc123"
 + # This will also print lines which have less than 5 fields.
 + awk '$5 != "abc123"'
 + awk '!($5 == "abc123")'
 +
 + # matching a field against a regular expression
 + awk '$7  ~ /^[a-f]/'    # print line if field #7 matches regex
 + awk '$7 !~ /^[a-f]/'    # print line if field #7 does NOT match regex
 +
 + # print the line immediately before a regex, but not the line
 + # containing the regex
 + awk '/regex/{print x};{x=$0}'
 + awk '/regex/{print (NR==1 ? "match on line 1" : x)};{x=$0}'
 +
 + # print the line immediately after a regex, but not the line
 + # containing the regex
 + awk '/regex/{getline;print}'
 +
 + # grep for AAA and BBB and CCC (in any order on the same line)
 + awk '/AAA/ && /BBB/ && /CCC/'
 +
 + # grep for AAA and BBB and CCC (in that order)
 + awk '/AAA.*BBB.*CCC/'
 +
 + # print only lines of 65 characters or longer
 + awk 'length > 64'
 +
 + # print only lines of less than 65 characters
 + awk 'length < 64'
 +
 + # print section of file from regular expression to end of file
 + awk '/regex/,0'
 + awk '/regex/,EOF'
 +
 + # print section of file based on line numbers (lines 8-12, inclusive)
 + awk 'NR==8,NR==12'
 +
 + # print line number 52
 + awk 'NR==52'
 + awk 'NR==52 {print;exit}'          # more efficient on large files
 +
 + # print section of file between two regular expressions (inclusive)
 + awk '/Iowa/,/Montana/'             # case sensitive
 +
 +SELECTIVE DELETION OF CERTAIN LINES:
 +
 + # delete ALL blank lines from a file (same as "grep '.' ")
 + awk NF
 + awk '/./'
 +
 + # remove duplicate, consecutive lines (emulates "uniq")
 + awk 'a !~ $0; {a=$0}'
 +
 + # remove duplicate, nonconsecutive lines
 + awk '!a[$0]++'                     # most concise script
 + awk '!($0 in a){a[$0];print}'      # most efficient script
 +</code>
 +
 +=====Links=====
 +
 +  * [[https://www.youtube.com/watch?v=9YOZmI-zWok|AWK Basics - Youtube]]
awk.txt · Zuletzt geändert: 2025/05/05 14:06 von admin

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