In awk, /.../ is (sort of) a regex constant. man awk:
Quote:
3. Regular expressions
In the AWK language, records, fields and strings are often tested for matching a regular expression. Regular expressions are enclosed in slashes, and
expr ~ /r/
is an AWK expression that evaluates to 1 if expr "matches" r, which means a substring of expr is in the set of strings defined by r. With no match the expression evaluates to 0; replacing ~ with the "not match" operator, !~ , reverses the meaning. As pattern-action pairs,
/r/ { action } and $0 ~ /r/ { action }
are the same, and for each input record that matches r, action is executed. In fact, /r/ is an AWK expression that is equivalent to ($0 ~ /r/) anywhere except ...
So, your expression /$4 ~ "101"/ will try to match exactly this string : $4 ~ "101" - which it won't find in your sample file.
Try
which might do exactly what you targeted for.
I recently started as an intern and my manager wanted to see how well I would handle Korn Bourne shell scripting without any prior experience, I have prior programming experience but I keep running into syntax errors with AWK. Please take a look at my simple code and tell me what stupid mistake... (6 Replies)
I have written many awk commands which go in multiple lines.
I have this confusion many times.
Some time they work if i dont terminate them with "\" but some time error.
Some time in "if" statements between if and else if i dont use ";" it gives error but sometimes it doesnt.
The below... (4 Replies)
I don't get correct output when I run this command line:
nmap -sP failedhost.com | grep -i failed | awk -F '{print $6}'
I basically want it to return 'failedhost.com' but its just showing the output of the nmap scan. (8 Replies)
Hi I am trying to understand AWK syntax
so I tried this command which gives me the home directory of root
awk 'BEGIN { FS = ":"} {if ($1 == "root") print $6 }' /etc/passwd
I would know what are the following commands doing. The first one prints all /etc/passwd, second prints nothing.
... (4 Replies)
Little bit confusing while using awk :confused::confused:
In Sed while pattern search we can use "(double quotes)
i mean
$a=hello
$cat file.txt |sed -n "/$a/p"this thing work fine But if i use it in awk it's not working How could i do the substitution of pattern by a variables and the... (1 Reply)
i have a ksh code that needs to be written in AWK. can someone please help me here? :(
if }" | grep -c "$2") -gt 0 ] ; then
print - "found $2 in array ignore"
else
print - "did not find $2 in array ignore"
fi
ignore=4ty56r
ignore=er45ty
.
.
.
ignore=frhtg2 (27 Replies)
I have a file which is comma separated and has quotes. I can use this command and
awk -F"," '{ if ($4=="01" print $0 }' test.txt
But this doesn't fetch me the data.since it has quotes.
If the data has no quotes,the above command works fine.
In Unix you can skip quote \" but this doesn't work.... (7 Replies)
Hi I have a bash file which will split a big file to many small files.
But I got a syntax error.H="$(head -1 CCC.tped)"
awk 'print $0 > $1 ".tped"' CCC.tped
for f in $(ls *.tped); do echo "$H\n" "$(cat $f)" >$f; done
And
-bash-4.1$ bash split
awk: print $0 > $1".tped"
awk: ^ syntax error... (3 Replies)
Hello Experts:
While writing a script to help one of the posts on here, I end up writing a wrong one. I am very much eager to know how this can be corrected.
Aim was to not print specified columns - lets say out of 100 fields, need to print all but 5th, 10th, 15th columns.
Someone already... (13 Replies)
Discussion started by: juzz4fun
13 Replies
LEARN ABOUT V7
expr
EXPR(1) General Commands Manual EXPR(1)NAME
expr - evaluate arguments as an expression
SYNOPSIS
expr arg ...
DESCRIPTION
The arguments are taken as an expression. After evaluation, the result is written on the standard output. Each token of the expression is
a separate argument.
The operators and keywords are listed below. The list is in order of increasing precedence, with equal precedence operators grouped.
expr | expr
yields the first expr if it is neither null nor `0', otherwise yields the second expr.
expr & expr
yields the first expr if neither expr is null or `0', otherwise yields `0'.
expr relop expr
where relop is one of < <= = != >= >, yields `1' if the indicated comparison is true, `0' if false. The comparison is numeric if
both expr are integers, otherwise lexicographic.
expr + expr
expr - expr
addition or subtraction of the arguments.
expr * expr
expr / expr
expr % expr
multiplication, division, or remainder of the arguments.
expr : expr
The matching operator compares the string first argument with the regular expression second argument; regular expression syntax is
the same as that of ed(1). The (...) pattern symbols can be used to select a portion of the first argument. Otherwise, the
matching operator yields the number of characters matched (`0' on failure).
( expr )
parentheses for grouping.
Examples:
To add 1 to the Shell variable a:
a=`expr $a + 1`
To find the filename part (least significant part) of the pathname stored in variable a, which may or may not contain `/':
expr $a : '.*/(.*)' '|' $a
Note the quoted Shell metacharacters.
SEE ALSO ed(1), sh(1), test(1)DIAGNOSTICS
Expr returns the following exit codes:
0 if the expression is neither null nor `0',
1 if the expression is null or `0',
2 for invalid expressions.
EXPR(1)