I am trying to perform this:
i have a test file which md5sum of files located on sftp.
variables should contain an md5sum (string), if the variable is empty it means there is no file on the sftp server.
i am trying this code but it does not work..
if [ -z $I_IDOCMD5 ] || [ -z $I_LEGALMD5 ] || [ -z $I_ZIPMD5 ]
then
echo "ERROR: At least one file not present of checksum missing no files will be deleted" >>$IN_LOG
ERRORS=$ERRORS+2
else
if [[ $I_IDOCMD5 == $($DIGEST -a md5 $SAPFOLDER/inward/idoc/$I_IDOC) ]]
then
echo "rm IDOC/$I_IDOC" >/SAP/commands_sftp.in
else
echo "problem with checksum"
ERRORS=$ERRORS+2
fi
if [[ $I_LEGALMD5 == $($DIGEST -a md5 $SAPFOLDER/inward/legal/$I_LEGAL) ]]
then
echo "rm LEGAL/$I_LEGAL" >>/SAP/commands_sftp.in
else
echo "problem with checksum"
ERRORS=$ERRORS+2
fi
if [[ $I_ZIPMD5 == $($DIGEST -a md5 $SAPFOLDER/inward/zip/$I_ZIP) ]]
then
echo "rm ZIP/$I_ZIP" >>/SAP/commands_sftp.in
else
echo "problem with checksum"
ERRORS=$ERRORS+2
fi
The answer I prefer is following
[[ -z "$1" ]] && { echo "Parameter 1 is empty" ; exit 1; }
Note, don't forget the ; into the {} after each instruction
One way to check if a variable is empty is:
if [ "$var" = "" ]; then
# $var is empty
fi
Another, shorter alternative is this:
[ "$var" ] || # var is empty
In bash you can use set -u which causes bash to exit on failed parameter expansion.
From bash man (section about set builtin):
-u
Treat unset variables and parameters other than the special parameters "#" and "*" as an error when performing parameter
expansion. If expansion is attempted on an unset variable or
parameter, the shell prints an error message, and, if not interactive,
exits with a non-zero status.
For more information I recommend this article:
http://redsymbol.net/articles/unofficial-bash-strict-mode/
You can use a short form:
FNAME="$I_IDOCMD5"
: ${FNAME:="$I_LEGALMD5"}
: ${FNAME:="$I_ZIPMD5"}
: ${FNAME:?"Usage: $0 filename"}
In this case the script will exit if neither of the I_... variables is declared, printing an error message prepended with the shell script line that triggered the message.
See more on this in abs-guide (search for «Example 10-7»).
First test only this (just to narrow it down):
if [ -z "$I_IDOCMD5" ] || [ -z "$I_LEGALMD5" ] || [ -z "$I_ZIPMD5" ]
then
echo "one is missing"
else
echo "everything OK"
fi
echo "\"$I_IDOCMD5\""
echo "\"$I_LEGALMD5\""
echo "\"$I_ZIPMD5\""
"if the variable is empty it means there is no file on the sftp server"
If there is no file on the sftp server, is the variable then really empty ?
No hidden spaces or anything like that ? or the number zero (which counts as non-empty) ?
Related
i have a file called MYNAME in path /root/user/
which has some value say SSS_14_10_1992
when the values exists in file the below code works fine
but when the file is empty , then the below mentioned error is thrown
i am reading this value from file and matching it wildcard and doing something , when the file has some value the below code works fine , when the file is empty then i am getting conditional error
Below is my code
var=$(cat /root/user/MYNAME)
echo $var
su - uname<<!
pwd
if [ -z "$var" ]; then
echo "NAME SHOULD BE PROVIDED IN MYNAME FILE"
else
if [[ $var == SSS_14_10* ]]
then
echo "value is matched"
else
echo "value has not matched"
fi
fi
!
when the file is empty
i am getting the below error:
: conditional binary operator expected
: syntax error near `SSS_14_10*'
: ` if [[ == SSS_14_10* ]]'
Try to compare "$var" (with quotes) instead of $var (without quotes). This way if the variable is empty you're just comparing "".
Don't generate code dynamically like this. Pass the value of $var as a parameter to the script run by su.
var=$(cat /root/user/MYNAME)
echo "$var"
su - uname<<'!' "$var"
pwd
if [ -z "$1" ]; then
echo "NAME SHOULD BE PROVIDED IN MYNAME FILE"
elif [[ $1 == SSS_14_10* ]]; then
echo "value is matched"
else
echo "value has not matched"
fi
!
Note the single quotes around the here-doc delimiter; this ensures the here document is seen as-is by su, so that nothing further needs escaping.
I am making a script for my school, and I was wondering how I could check a file, and if the string isn't in the file, do a code, but if it is, continue, like this:
while [ -z $(cat File.txt | grep "string" ) ] #Checking if file doesn't contain string
do
echo "No matching string!, trying again" #If it doesn't, run this code
done
echo "String matched!" #If it does, run this code
You can do something like:
$ if grep "string" file;then echo "found";else echo "not found"
To do a loop :
$ while ! grep "no" file;do echo "not found";sleep 2;done
$ echo "found"
But be carefull not to enter an infinite loop. string or file must be changed otherwise the loop has no meaning.
Above if/while works based on the return status of the command and not on the result.
if grep finds string in file will return 0 = success = true
if grep does not find string will return 1 = not success = false
By using ! we revert the "false" to "true" to keep the loop running since while loops on something as soon as it is true.
A more conventional while loop would be similar to your code but without the useless use of cat and the extra pipe:
$ while [ -z $(grep "no" a.txt) ];do echo "not found";sleep 2;done
$ echo "found"
A simple if statement to test if a 'string' is not in file.txt:
#!/bin/bash
if ! grep -q string file.txt; then
echo "string not found in file!"
else
echo "string found in file!"
fi
The -q option (--quiet, --silent) ensures output is not written to standard output.
A simple while loop to test is a 'string' is not in file.txt:
#!/bin/bash
while ! grep -q string file.txt; do
echo "string not found in file!"
done
echo "string found in file!"
Note: be aware of the possibility that the while loop may cause a infinite loop!
Another simple way is to just do the following:
[[ -z $(grep string file.file) ]] && echo "not found" || echo "found"
&& means AND - or execute the following command if the previous is true
|| means OR - or execute if the previous is false
[[ -z $(expansion) ]] means return true if the expansion output is null
This line is much like a double negative, basically:
"return true if the string is not found in file.file; then echo not found if true, or found if false"
Example:
bashPrompt:$ [[ -z $(grep stackOverflow scsi_reservations.sh) ]] && echo "not found" || echo "found"
not found
bashPrompt:$ [[ -z $(grep reservations scsi_reservations.sh) ]] && echo "not found" || echo "found"
found
I want to check, if multiple variable are set or not, if set then only execute the script code, otherwise exit.
something like:
if [ ! $DB=="" && $HOST=="" && $DATE=="" ]; then
echo "you did not set any variable"
exit 1;
else
echo "You are good to go"
fi
You can use -z to test whether a variable is unset or empty:
if [[ -z $DB || -z $HOST || -z $DATE ]]; then
echo 'one or more variables are undefined'
exit 1
fi
echo "You are good to go"
As you have used the bash tag, I've used an extended test [[, which means that I don't need to use quotes around my variables. I'm assuming that you need all three variables to be defined in order to continue. The exit in the if branch means that the else is superfluous.
The standard way to do it in any POSIX-compliant shell would be like this:
if [ -z "$DB" ] || [ -z "$HOST" ] || [ -z "$DATE" ]; then
echo 'one or more variables are undefined'
exit 1
fi
The important differences here are that each variable check goes inside a separate test and that double quotes are used around each parameter expansion.
If you are ok with writing a function for this purpose, it can be pretty convenient.
This solution uses the ${!VAR_NAME} syntax to check whether the variable is empty and has the added benefit of telling you which variable names are empty.
check_vars()
{
var_names=("$#")
for var_name in "${var_names[#]}"; do
[ -z "${!var_name}" ] && echo "$var_name is unset." && var_unset=true
done
[ -n "$var_unset" ] && exit 1
return 0
}
# Usage for this case
check_vars DB HOST DATE
echo "You are good to go"
I wound up using variable-variables to loop through an easily managed HEREDOC list of variable names:
# Ensure non-empty values.
# Loop through HEREDOC, test variable-variable isn't blank.
while read var; do
[ -z "${!var}" ] && { echo "$var is empty or not set. Exiting.."; exit 1; }
done << EOF
KUBE_NAMESPACE
DOCKER_REGISTRY
DOCKER_DEPLOY_USER
DOCKER_DEPLOY_PASSWORD
DOCKER_DEPLOY_EMAIL
EOF
You can check it also by put the variables name in a file
DB=myDB
HOST=myDB
DATE=myDATE
then test them if currently empty or unset
#!/bin/bash
while read -r line; do
var=`echo $line | cut -d '=' -f1`
test=$(echo $var)
if [ -z "$(test)" ]; then
echo 'one or more variables are undefined'
exit 1
fi
done <var.txt
echo "You are good to go"
Nice solution from #joe.still !
improvement is to exit after checking all variables
i=0
while read var; do
[ -z "${!var}" ] && { echo "$var is empty or not set. Exiting.."; let i=i+1; }
done << EOF
KUBE_NAMESPACE
DOCKER_REGISTRY
DOCKER_DEPLOY_USER
DOCKER_DEPLOY_PASSWORD
DOCKER_DEPLOY_EMAIL
EOF
if [ $i -gt 0 ]; then
echo $i
echo "exiting"
exit 1
fi
Good Day Everyone.
I've personally used this method in my bash scripts. Verified works on bash 4.4 and later in Ubuntu, openSUSE, and ClearLinux.
Can RHEL|CentOS|Alma and Arch Based users let me know it it works fine for you?
( [ "$VAR1""$VAR2""$VAR3""$VAR4""$VAR5" ] && echo -e " Warning: StackIsNotClear" ) || { echo -e " GoodNews: StackIsClear"; }
I'm trying to write a short bash script that optionally accepts arguments from the command line, or prompts for their input
if [ [ -z "$message" ] && [ -z "$predefined" ] ] ; then
read -p "Enter message [$defaultMessage]: " message
message=${message:-$defaultMessage}
else
if [ -n "$predefined" ]; then
if [ -f $base/$environment/vle/data/$predefined.txt ]; then
echo Predefined message file $predefined.txt does not exist
exit 1
fi
fi
fi
If neither message nor predefined has been passed in as command line arguments, then the code should prompt for a value for message; otherwise if predefined has been passed in as a command line argument, then the script should test for the existence of a file of that name and only continue if the file does exist
But I'm getting the following error
[: -z: binary operator expected
at the first of those if tests
Any help in explaining what's wrong with my syntax for that first if statement? Or providing an alternative syntax to achieve the same objectives.
The first if is not well-formed. This would work:
if [ -z "$message" ] && [ -z "$predefined" ]; then
or this:
if test -z "$message" && test -z "$predefined"; then
or this bash-specific, easy but dirty way:
if [[ -z "$message" ]] && [[ -z "$predefined" ]]; then
or this bash-specific proper way:
if [[ -z $message && -z $predefined ]]; then
In this last version the double-quotes are unnecessary, not a typo.
Thanks #mklement0 for the corrections in the bash-specific style, and for this final comment:
I should note that there's one case where double-quoting is still a must inside [[ ... ]], namely if you want a variable reference on the right side of a string comparison (==) to be treated as a literal:
v='[a]'
[[ $v == $v ]] # FALSE!
[[ $v == "$v" ]] # true
Without double-quoting, the right-hand side is interpreted as a pattern. Some people advocate always double-quoting variable references so as not to have to remember such subtleties. That said (from bash 3.2 on), you must NOT double-quote the right operand when regex matching with =~
test expression1 -a expression2
is true if both expressions are true.
test expression1 -o expression2
is true if either or both expressions are true.
if [ -z "$message" -a -z "$predefined" ]; then
read -p "Enter message [$defaultMessage]: " message
message=${message:-$defaultMessage}
else
if [ -n "$predefined" -a -f $base/$environment/vle/data/$predefined.txt ]; then
echo Predefined message file $predefined.txt does not exist
exit 1
fi
fi
This was able to combine 4 test into 2 while also getting rid of one nested if expression; then ; fi
This may turn out to be more of a thought exercise, but I am trying to echo a newline after some command I'm executing within a conditional. For example, I have:
if ssh me#host [ -e $filename ] ; then
echo "File exists remotely"
else
echo "Does not exist remotely"
fi
And want to throw in an echo after the ssh command regardless of the outcome. The reason is formatting; that way a newline will exist after the prompt for password for ssh.
First Try
if ssh me#host [ -e $filename ] && echo ; then
Because && echo would not change the conditional outcome, but bash would not execute echo if ssh returned false. Similarly,
if ssh me#host [ -e $filename ] || (echo && false) ; then
Does not work because it will short-circuit if ssh returns true.
An answer to the problem would be
ssh me#host [ -e $filename ]
result=$?
echo
if [ $result == 0 ] ; then
but was wondering if there was some similar conditional expression to do this.
Thanks.
While this would work
if foo && echo || ! echo; then
I'd prefer putting the whole thing into a function
function addecho() {
"$#" # execute command passed as arguments (including parameters)
result= $? # store return value
echo
return $result # return stored result
}
if addecho foo; then
What about this?
if ssh me#host [ -e $filename ] && echo || echo; then
I have not thought about precedence order of && and || and surely putting some parenthesis would help, but like that it works already... you get the echo both when ssh fails and when it succeeds...
Add the "echo" before the filename test
if ssh me#host "echo; [ -e $filename ]"; then
echo "File exists remotely"
else
echo "Does not exist remotely"
fi