[[ ... ]] supports everything [ ... ] does and more, it's an extended syntax. I am supposed to be getting into the habit of using [[ ... ]] all the time as pretty much mandated by standard now, but it's a hard habit to break.
No. The POSIX standards and the Single UNIX specifiations do not yet specify [[ ... ]].
Note that test and its synonym [ are (built-in) utilities, while [[ expression ]] is a part of the shell programming language (l.e., [[ is a keyword not a utility name).
A bug report (#375) was filed in February 2011 that has morphed into a proposal to include a subset of the expressions some shells support with:
syntax in the next revision of the standards. But even with the comments added last month, we still don't have a proposal that is likely to pass ballot requirements (at least 75% approval) to become part of the standards yet.
This User Gave Thanks to Don Cragun For This Post:
I have a directory that contains a number of history files for a process. Every file starts with the string "EVACK". FOr example
EVACK0101.000001
EVACK0102.095940
EVACKmmdd.hhmiss
I want to erase in the specific directory ONLY(no sub-directories) all EVACK files older then 90 days. I... (2 Replies)
Hello all
Im trying to write one liner that will show me results only if the result of the expression is greater then 0
For example:
I do :
find . -name "*.dsp" | xargs grep -c SecurityHandler
the result are :
./foo/blah/a.dsp:0
./foo/blah1/b.dsp:1
./foo/blah2/c.dsp:2... (1 Reply)
HI All,
I have a file with contents like this:
apple
computer
terminal
applecomputernetworkrouterterminalrouter
network
router
applecomputernetworkrouterterminalrouter
I want to remove all lines with length greater than "18 alphabets". Hence, my output should be:
apple
computer... (1 Reply)
Hello,
In my code I am checking to see if a variable that contains a decimal number is greater than 0 in the following manner:
if
do something
fi
However I am getting the error message (if $i for the current iteration holds 9.6352)
command 9.6352 is not found
How can I rectify... (5 Replies)
Hi all,
I have a tab-delimited text file of size 10Mb. I am trying to count the number of lines using,
grep -c . sample.txtor
wc -l < sample.txt or
awk 'END {print NR}' sample.txtAll these commands shows the count as 1, which means they are reading only the first header line of the file.... (3 Replies)
A newbie question...
I need to get a list of the Files and folders which are greater then a specific date. I want write the output to a Text file.
What I know ls -lrt gives me list of all the files ordered by date. Also ls > fileName will write the results to a text file.
Please help (6 Replies)
data:
hello mr smith 400 you all ok?
hello mrs. smith 700 you all ok?
hello mr. everyone 150 you all ok?
hello mr. you all 199 im lad you are ok
using egrep, how can i grep out only lines that have a number greater than 250?
cat data | egrep .....
can't use awk here. i was... (7 Replies)
i'm aware awk can do what i'm trying to do here. but i cant use awk in this scenario given the circumstance of this box.
but i need to check if a number is a certain column is over a certain value, say for instance, 20.
data:
| 12 | 19 | 2000 | 9029333 |... (11 Replies)
Hello,
I am newbie to bash scripting. Could someone help me with the following.
I have log file with output as shown below
**************************LOG*************************
11/20/2013 9:11:23.64 Pinging xx.xx.xx.xx with 32 bytes of data:
11/20/2013 9:11:23.64 Reply from xx.xx.xx.xx:... (4 Replies)