Questions tagged [test]
This is about the Unix utility "test," also invoked as "[", or its shell syntax [[ … ]] variant. For questions about testing software and setups, use the "testing" tag.
295
questions
2
votes
0answers
36 views
Testing whether an executable can be run on Linux? [duplicate]
In my Ubuntu packages, I install a hook with a one liner script:
if test -x /usr/bin/snapsignal
then
/usr/bin/snapsignal "snapmanagerdaemon/DPKGUPDATE hook_action=\"$DPKG_HOOK_ACTION\""
fi
(...
1
vote
0answers
85 views
What is the difference between test, [, and [[ in terms of binary vs. builtin? [duplicate]
It is often written:
/usr/bin/test is a synonym for /usr/bin/[
[[ is a bash improvement for [
test and [ are also builtins
I understand the difference between [ and [[ but I am confused with the ...
1
vote
1answer
53 views
What does the -a unary operator check?
I have just found a couple of examples using [ -a some_dir ] or [ -a some_file ] but can't find what the -a operator is for. It seems it should be described in the man page for test/[ but there it is ...
2
votes
1answer
72 views
How to determine if result of process substitution is a file path
If I do this:
echo <(cat)
I get:
/dev/fd/63
so say at the command line I have:
myapp -f <(cat)
when I run it I get this error:
You need to pass a file after the -f flag. The resolved ...
0
votes
1answer
59 views
Bash script to compare ASCII values [closed]
what is the wrong?
#!/usr/local/bin/bash
REF_FILE_NUM="000000010000001900000052"
for id in `ls -1 dir` ;
do
FILE_NUM=${id:0:24}
echo "FILE_NUM: $FILE_NUM ; REF_FILE_NUM: $REF_FILE_NUM"
if [[ "$...
2
votes
3answers
74 views
Shortcutting in a loop
Shortcutting: (expr1 && expr2), rather than an if ... fi statement. If expr1, expr2,... are to be generated by a loop, can you do it?
Here's a toy example:
$ for cond in {0,0,0}; do if [[ $...
0
votes
3answers
97 views
I would like to check if a file name matches a certain pattern
I would like to check if a file name matches a certain pattern start with an alphanumeric character ([a-zA-Z0-9]) and will only contain alpha-numeric characters plus '.', '-' and '_' characters.
...
3
votes
1answer
70 views
Comparing exit code: unary operator expected [duplicate]
I have a list of git commits in a .txt file and I want to iterate over the commits. For each COMMIT_ID I want check them using a git command whose exit code is 0 or 1.
Depending on the result I want ...
0
votes
2answers
47 views
Print all subdirectories in the current directory that do not contain a .git
I'm trying to write a bash line that will look at all the subdirectories in my current folder and tell me if any do NOT contain a ".git". Pseudo:
for subdir in currentdir
if .git does not exist
...
0
votes
3answers
68 views
I have if else question but I am not sure the answer is true? [duplicate]
I am running this on Linux:
$ number=4
$ test $number -eq 4
$ echo $?
0
$ test $number -lt 2
$ echo $?
1
Are the results (0 and 1) true ?
0
votes
1answer
63 views
Why does “if tty -s” work but “if [ tty -s ]” does not?
Note, I am using ksh and running in CentOS.
I have a shell script where a logger function is set like:
if tty -s
then
echo "${FOO}" | tee -a ${BAR_LOG_FILE}
else
echo "${FOO}" >> ${...
-1
votes
2answers
98 views
How to test file permissions using shell script?
I am testing if my file has read permissions, by running this script as root:
#!/usr/bin/env bash
FILE="/etc/shadow"
if ! [ -r $FILE ]; then
echo "Hello"
fi
exit 0
Ideally, script has to print ...
2
votes
1answer
85 views
How to check for presence of named pipe on the file system [duplicate]
I tried using the -f flag to test if a named pipe is present
if [[ ! -f "$fifo" ]]; then
echo 'There should be a fifo.lock file in the dir.' > /dev/stderr
return 0;
fi
this check does not ...
2
votes
1answer
150 views
Bash: Regex for comparing file path
I want to check if an input string matches whitelisted file paths, then only I want to perform some operation.
I am doing something like this
path1="mydir/**"
path2="mydir/testing"
[ [ "$path2" =~ "...
3
votes
2answers
86 views
Bash difference or preferred negation statement
Is there a difference in bash, or a preferred usage of negation of a statement?
if ! [[ -z "${var}" ]]; then
do_something
fi
Versus
if [[ ! -z "${var}" ]]; then
do_something
fi
1
vote
1answer
60 views
Grep to check filesystem mount and test to check for file path is providing incorrect information
Even though the path exists, this script reports that it does not. What is the flaw in the logic?
#!/bin/bash
mount="/fileserver"
if grep -qs "$mount" /proc/mount && { test -d '/fileserver/...
1
vote
1answer
45 views
Shell script to test ls output for directories
I am trying to make a BASH script to test the files in the working directory and return the files that are directory files.
One approach that I can think of is, starting with ls and feeding the ...
-1
votes
1answer
30 views
why does test command startswith fail (exit with 1)?
I have this test command:
test "ssh://hg@bitbucket.org/teros/moodwire_demo" == ssh*; echo $?
why does it exit with 1? I am trying to see if the first string starts with the second string.
0
votes
1answer
57 views
if statement not working inside while loop
I don't understand why comparing strings is not working here:
while IFS=, read -r ELMS_SIZE ELMS_NAME ELMS_ENV ELMS_DB
do
if [ "${ELMS_DB}" = "NOMATCH" ]; then
echo "done"
fi
done < <(tac ${...
5
votes
2answers
78 views
How do I test for link to a link?
I want to test whether a file is a link to another link. I tried readlink but it doesn't work the way I need it:
ralph@bash4.4.12,1:~/subdir1 $ ll
lrwxrwxrwx 1 pi pi 13 Apr 10 14:34 hellolink ->...
1
vote
0answers
24 views
bc command unexpected results [duplicate]
I am trying to compare a decimal and it seems like bc is ignoring it. The OS is CentOS release 6.9 (Final) and bash is bash-4.1.2-48.el6.x86_64, below is the code
#!/bin/sh
i=32.39
IP_LOW_2=32.0
...
3
votes
2answers
61 views
Exit statuses of comparisons in test constructs
I was writing some "if then" statements and found what seemed to me an odd behavior. Upon investigation I realized that it boiled down to the exit code of the comparison I was making. I illustrate my ...
1
vote
3answers
146 views
“==” logical operator and zsh version 5.7.x (installed using Homebrew)
Been getting errors on my scripts when using this operator. I've some online documentation and double equals should supposedly work. Any ideas?
Zsh reference guide: http://zsh.sourceforge.net/Doc/...
23
votes
5answers
2k views
Why use double quotes in a [[ ]] test?
Let's say we have 2 integers in a bash script:
value1=5
value2=3
Then why do we need to use double quotes in case of a test ? For example:
if [[ "$value1" -eq "$value2" ]]
Why not just use the ...
1
vote
2answers
176 views
Solaris script - modified date file age
I have a bash script on a Solaris server to provide an alert if a file is in a folder location for longer than 5 minutes.
if [ -f $1 ]
then
a=0
else
a=1
However, it is throwing a lot of false ...
0
votes
0answers
30 views
Solaris - modified date file age [duplicate]
I have a bash script on a Solaris server to provide an alert if a file is in a folder location for longer than 5 minutes.
It seems the -mmin command doesn't work in Solaris.
if [ -f $1 -mmin +15 ]
...
3
votes
2answers
129 views
A Unix AIX variable without a $ symbol?
I'm trying to debug an existing program and found an if condition without $ symbol prefixed to it.
Values are:
dt_val=1234
prev_dt_val=1234
If condition goes like:
if [ dt_val -eq prev_dt_val ]
...
1
vote
1answer
2k views
Error [: -lt: unary operator expected in shell script Linux [closed]
I get error [: -lt: unary operator expected after run below script, anyone can share ideas?
temp=0
while [ $temp -lt 25 ]
do
sleep 1
echo "running.."
if [ $temp -eq 5 ]
then
...
3
votes
3answers
397 views
Union commands after the || (OR) operator
When I write the code the way below, I am able to run several commands after the else statement:
if [ "$?" -eq 0 ]
then
echo "OK"
else
echo "NOK"
exit 1
...
4
votes
2answers
146 views
What's the purpose of adding a prefix on both sides of a shell variable comparison to a string literal?
I have encountered comparisions of variables to string literals multiple times over the years which had one character prefixing the variable and the literal, e.g.
if [ "x$A" = "xtrue" ]; then
in ...
0
votes
2answers
60 views
auto install minecraft script
So I was working on this script to auto install minecraft and i began to wonder is there a better way to do this?
#!/bin/bash
sudo apt-get upgrade
sudo apt-get update
sudo apt-get autoclean
echo " ...
1
vote
1answer
210 views
-w flag in bash if statement not working
I have a simple script that checks if a file has write permission on it or No. If yes, then it allows the user to append some text data to end of file. If No, it kicks user back out.
I am following a ...
0
votes
2answers
158 views
java -version In Bash Script. Giving integer error
I am trying to make this if..fi case work for the Java Version from wrapper.conf configuration file./ and from the system, If the output from wrapper.conf is java
I would have two options;
1. ...
0
votes
1answer
1k views
[: =: unary operator expected [duplicate]
I need to write a script to test if a service inside of an Android emulator is ready for apk installation or not using this command
adb -s emulator-5554 shell pm list package | grep package:com....
2
votes
1answer
81 views
Running a Test with expression in a string
I am trying to run the test command from a string. The string contains the expression.
TEST="! -e ~/bin/xyz"
if [ `echo "$TEST"` ]; then
echo running "$TEST";
fi
However, the above if ...
10
votes
3answers
3k views
Schedule the last day of every month
I read from an instruction to schedule a script on the last day of the month:
Note:
The astute reader might be wondering just how you would be able to set a command to execute on the last day of ...
1
vote
2answers
107 views
bash script get result from test into variable
I'm trying to learn Bash scripting and for fun I would like to write a script which will monitor the httpd.service.
The basic construct looks like this:
#!/bin/bash
SERVICE=httpd.service
if [ "...
0
votes
2answers
3k views
Determining if the first string starts with second string
JavaScript has a function for this:
'world'.startsWith('w')
true
How can I test this with shell? I have this code:
if [ world = w ]
then
echo true
else
echo false
fi
but it fails because it is ...
2
votes
2answers
67 views
Why does test -e fail on a file in a directory with only read permissions?
From what I understand about the read permission on directories, it allows listing of which files are in a directory and that's about it.
Given a directory with 0744 permissions, owned by userA:
[...
1
vote
3answers
837 views
check whether the user has a password set for his account in a script
I'm writing a script and need to check $user if his account has a password set, how can I do this?
I know about this:
passwd --status username
Display account status information. The status ...
0
votes
1answer
97 views
If statement works with [ but not with [[ when comparing strings with -eq [duplicate]
My code:
#!/bin/bash
x=${#}
for (( a=0; a<x; ++a)); do
if [[ $1 -eq $1 ]] 2> /dev/null
then
variable[a]=${1}
shift
else
echo "The argument $1 is NOT an integer. ...
4
votes
3answers
515 views
Mixing if ..; with { command-grouping} and [[ test ]] and logical operators [closed]
Edit: I've tried again and now it works fine in bash. I don't know what changed. My editor (VS Code with Bash IDE extension) still gives me a failed to parse error, but the script runs properly. ...
-1
votes
1answer
90 views
Bash: How to escape minus in `if [ … ` (alias “test”)?
I need to test this:
kill -0 $LAST_PID;
So I wrote
if [ kill -0 $LAST_PID ] ; then ...
But this results in an error - unknown operator after - or so.
how do I escape the options within if?
0
votes
1answer
1k views
Empty string is a file? ( if [ ! -f “” ] )
The script is called isFile.sh and looks like this:
#!/bin/sh
echo $1
echo $2
if [ ! -f $1 ]; then
echo "$1 (arg1) is not a file"
fi
if [ ! -f $2 ]; then
echo "$2 (arg2) is not a file"
fi
...
2
votes
1answer
299 views
How to check if there are “other” permissions in home directories
Right now, I have a script that runs daily that chmod's the home directories, removing all "other" permissions from the directories and the "group" write permission. See below.
#Removing all other ...
1
vote
3answers
273 views
Alternative to Bash double bracket glob match
Given
hasArgs=a:b:c:
x=b
if [[ ${hasArgs} = *$x:* ]] ; then …
I wish I could replace the above double brackets test with a less Bash specific alternative (meaning no subshell/command etc.)
...
0
votes
0answers
19 views
Command substitution, assignment, tests and spaces [duplicate]
I know the whole language is confusing, but I am having trouble understanding assignments with command substitutions:
x=Example sentence #1 fails due to space
x='Example sentence' ...
4
votes
3answers
877 views
Clarification on differences and usage of test -f vs test -e in a shell script
In a code review
I am being pointed out that I should change such a test structure:
[ ! -f "$1" ] &&
print_error_and_exit "The given argument is not an existing file."
to something similar, ...
1
vote
2answers
215 views
Similar test expressions using or operator?
Just wondering if this:
if [ "$first_arg" == "major" ] || [ "$first_arg" == "minor" ]; then
exit 1;
fi
is the same as this:
if [ "$first_arg" == "major" || "$first_arg" == "minor" ]; then
...
11
votes
3answers
850 views
Performing -nt/-ot test in a POSIX sh
The built-in test and [ utilities have the -nt ("newer than") and -ot ("older than") tests in most shells, even when the shell is running in "POSIX mode" (also true for the external utilities of the ...
