Im just wondering if there is any way to say 'if chmod does not change permissions of the file, then ...'
if ! chmod ${1} ${2} #if chmod did not excecute correctly
then
echo "${0}:ERROR: ${2} has not been changed." 1>&2
exit 6 #exiting due to failure. status 6
fi
I have tried this and several other ways but I can only add to the current setting rather than change it...
i.e if i start with -rwxr-xr-x i change it to -rwxrwxrwx
nothing else seems to work
Your command is correct. But it only detects when the chmod can not operate (e.g. when you don't own the file, when the FS is read-only, etc.).
If you also want to detect that the chmod didn't change anything, try this:
if ! res=$(chmod -c -- "${1}" "${2}") || [ -z "$res" ]
then
echo "${0}:ERROR: ${2} has not been changed." 1>&2
exit 6 #exiting due to failure. status 6
fi
The -c flag is specific to GNU chmod. Here is the description:
-c, --changes
like verbose but report only when a change is made
-v, --verbose
output a diagnostic for every file processed
Related
I am trying to automate out a lot of our pre fs/db tasks and one thing that bugs me is not knowing whether or not a command i issue REALLY happened. I'd like a way to be able to watch for a return code of some sort from executing that command. Where if it fails to rm because of a permission denied or any error. to issue an exit..
If i have a shell script as such:
rm /oracle/$SAPSID/mirrlogA/cntrl/cntrl$SAPSID.ctl;
psuedo code could be something similar to..
rm /oracle/$SAPSID/mirrlogA/cntrl/cntrl$SAPSID.ctl;
if [returncode == 'error']
exit;
fi
how could i for example, execute that rm command and exit if its NOT rm'd. I will be adapting the answer to execute with multiple other types of commands such as sed -i -e, and cp and umount
edit:
Lets suppose i have a write protected file such as:
$ ls -lrt | grep protectedfile
-rwx------ 1 orasmq sapsys 0 Nov 14 12:39 protectedfile
And running the below script generates the following error because obviously theres no permissions..
rm: remove write-protected regular empty file `/tmp/protectedfile'? y
rm: cannot remove `/tmp/protectedfile': Operation not permitted
Here is what i worked out from your guys' answers.. is this the right way to do something like this? Also how could i dump the error rm: cannot remove /tmp/protectedfile': Operation not permitted` to a logfile?
#! /bin/bash
function log(){
//some logging code, simply writes to a file and then echo's out inpit
}
function quit(){
read -p "Failed to remove protected file, permission denied?"
log "Some log message, and somehow append the returned error message from rm"
exit 1;
}
rm /tmp/protectedfile || quit;
If I understand correctly what you want, just use this:
rm blah/blah/blah || exit 1
a possibility: a 'wrapper' so that you can retrieve the original commands stderr |and stdout?], and maybe also retry it a few times before giving up?, etc.
Here is a version that redirects both stdout and stderr
Of course you could not redirect stdout at all (and usually, you shouldn't, i guess, making the "try_to" function a bit more useful in the rest of the script!)
export timescalled=0 #external to the function itself
try_to () {
let "timescalled += 1" #let "..." allows white spaces and simple arithmetics
try_to_out="/tmp/try_to_${$}.${timescalled}"
#tries to avoid collisions within same script and/or if multiple script run in parrallel
zecmd="$1" ; shift ;
"$1" "$#" 2>"${try_to_out}.ERR" >"${try_to_out}.OUT"
try_to_ret=$?
#or: "$1" "$#" >"${try_to_out}.ERR" 2>&1 to have both in the same one
if [ "$try_to_ret" -ne "0" ]
then log "error $try_to_ret while trying to : '${zecmd} $#' ..." "${try_to_out}.ERR"
#provides custom error message + the name of the stderr from the command
rm -f "${try_to_out}.ERR" "${try_to_out}.OUT" #before we exit, better delete this
exit 1 #or exit $try_to_ret ?
fi
rm -f "${try_to_out}.ERR" "${try_to_out}.OUT"
}
it's ugly, but could help ^^
note that there are many things that could go wrong: 'timecalled' could become too high, the tmp file(s) could not be writable, zecmd could contain special caracters, etc...
Usualy some would use a command like this:
doSomething.sh
if [ $? -ne 0 ]
then
echo "oops, i did it again"
exit 1;
fi
B.T.W. searching for 'bash exit status' will give you already a lot of good results
I'm trying to create a shell script that I will download the latest Atomic gotroot rules to my server, unpack them, copy them to the correct folder, etc.,
I've been reading shell tutorials and forum posts for most of the day and the syntax escapes me for some of these. I have run all these commands and I know they work if I manually run them.
I know I need to develop some error checking, but I'm just trying to get the commands to run correctly. The main problem at the moment is the syntax of the wget commands, i've got errors about missing semi-colons, divide by zero, unsupported schemes - I've tried various quoting (single and double) and escaping - / " characters in various combinations.
Thanks for any help.
The raw wget command is
wget --user="jim" --password="xxx-yyy-zzz" "http://updates.atomicorp.com/channels/rules/subscription/VERSION"
#!/bin/sh
update_modsec_rules(){
wget=/usr/bin/wget
tar=/bin/tar
apachectl=/usr/bin/apache2ctl
TXT="Script Run Finished"
WORKING_DIR="/var/asl/updates"
TARGET_DIR="/usr/local/apache/conf/modsec_rules/"
EXISTING_FILES="/var/asl/updates/modsec/*"
EXISTING_ARCH="/var/asl/updates/modsec-*"
WGET_OPTS='--user=jim --password=xxx-yyy-zzz'
URL_BASE="http://updates.atomicorp.com/channels/rules/subscription"
# change to working directory and cleanup any downloaded files and extracted rules in modsec/ directory
cd $WORKING_DIR
rm -f $EXISTING_ARCH
rm -f $EXISTING_FILES
rm -f VERSION*
# wget to download VERSION file
$wget ${WGET_OPTS} "${URL_BASE}/VERSION"
# get current MODSEC_VERSION from VERSION file and save as variable
source VERSION
TARGET_DATE=$MODSEC_VERSION
echo $TARGET_DATE
# wget to download current archive
$wget ${WGET_OPTS} "${URL_BASE}/modsec-${TARGET_DATE}.tar.gz"
# extract archive
echo "extracting files . . . "
tar zxvf $WORKING_DIR/modsec-${TARGET_DATE}.tar.gz
echo "copying files . . . "
cp -uv $EXISTING_FILES $TARGET_DIR
echo $TXT
}
update_modsec_rules $# 2>&1 | tee -a /var/asl/modsec_update.log
RESTART_APACHE="/usr/local/cpanel/scripts/restartsrv httpd"
$RESTART_APACHE
Here are some guidelines to use when writing shell scripts.
Always quote variables when you use them. This helps avoid the possibility of misinterpretation. (What if a filename contains a space?)
Don't trust fileglobbing on commands like rm. Use for loops instead. (What if a filename starts with a hyphen?)
Avoid subshells when possible. Your lines with backquotes make me itchy.
Don't exec if you can help it. And especially don't expect any parts of your script after your exec to actually get run.
I should point out that while your shell may be bash, you've specified /bin/sh for execution of this script, so it is NOT a bash script.
Here's a rewrite with some error checking. Add salt to taste.
#!/bin/sh
# Linux
wget=/usr/bin/wget
tar=/bin/tar
apachectl=/usr/sbin/apache2ctl
# FreeBSD
#wget=/usr/local/bin/wget
#tar=/usr/bin/tar
#apachectl=/usr/local/sbin/apachectl
TXT="GOT TO THE END, YEAH"
WORKING_DIR="/var/asl/updates"
TARGET_DIR="/usr/local/apache/conf/modsec_rules/"
EXISTING_FILES_DIR="/var/asl/updates/modsec/"
EXISTING_ARCH="/var/asl/updates/"
URL_BASE="http://updates.atomicorp.com/channels/rules/subscription"
WGET_OPTS='--user="jim" --password="xxx-yyy-zzz"'
if [ ! -x "$wget" ]; then
echo "ERROR: No wget." >&2
exit 1
elif [ ! -x "$apachectl" ]; then
echo "ERROR: No apachectl." >&2
exit 1
elif [ ! -x "$tar" ]; then
echo "ERROR: Not in Kansas anymore, Toto." >&2
exit 1
fi
# change to working directory and cleanup any downloaded files
# and extracted rules in modsec/ directory
if ! cd "$WORKING_DIR"; then
echo "ERROR: can't access working directory ($WORKING_DIR)" >&2
exit 1
fi
# Delete each file in a loop.
for file in "$EXISTING_FILES_DIR"/* "$EXISTING_ARCH_DIR"/modsec-*; do
rm -f "$file"
done
# Move old VERSION out of the way.
mv VERSION VERSION-$$
# wget1 to download VERSION file (replaces WGET1)
if ! $wget $WGET_OPTS $URL_BASE}/VERSION; then
echo "ERROR: can't get VERSION" >&2
mv VERSION-$$ VERSION
exit 1
fi
# get current MODSEC_VERSION from VERSION file and save as variable,
# but DON'T blindly trust and run scripts from an external source.
if grep -q '^MODSEC_VERSION=' VERSION; then
TARGET_DATE="`sed -ne '/^MODSEC_VERSION=/{s/^[^=]*=//p;q;}' VERSION`"
echo "Target date: $TARGET_DATE"
fi
# Download current archive (replaces WGET2)
if ! $wget ${WGET_OPTS} "${URL_BASE}/modsec-$TARGET_DATE.tar.gz"; then
echo "ERROR: can't get archive" >&2
mv VERSION-$$ VERSION # Do this, don't do this, I don't know your needs.
exit 1
fi
# extract archive
if [ ! -f "$WORKING_DIR/modsec-${TARGET_DATE}.tar.gz" ]; then
echo "ERROR: I'm confused, where's my archive?" >&2
mv VERSION-$$ VERSION # Do this, don't do this, I don't know your needs.
exit 1
fi
tar zxvf "$WORKING_DIR/modsec-${TARGET_DATE}.tar.gz"
for file in "$EXISTING_FILES_DIR"/*; do
cp "$file" "$TARGET_DIR/"
done
# So far so good, so let's restart apache.
if $apachectl configtest; then
if $apachectl restart; then
# Success!
rm -f VERSION-$$
echo "$TXT"
else
echo "ERROR: PANIC! Apache didn't restart. Notify the authorities!" >&2
exit 3
fi
else
echo "ERROR: Apache configs are broken. We're still running, but you'd better fix this ASAP." >&2
exit 2
fi
Note that while I've rewritten this to be more sensible, there is certainly still a lot of room for improvement.
You have two options:
1- changing this to
WGET1=' --user="jim" --password="xxx-yyy-zzz" "http://updates.atomicorp.com/channels/rules/subscription/VERSION"'
then run
wget $WGET1 same to WGET2
Or
2- encapsulating $WGET1 with backquotes ``.
e.g.:
`$WGET`
This applies to any command your executing out of a variable.
Suggested changes:
#!/bin/sh
TXT="GOT TO THE END, YEAH"
WORKING_DIR="/var/asl/updates"
TARGET_DIR="/usr/local/apache/conf/modsec_rules/"
EXISTING_FILES="/var/asl/updates/modsec/*"
EXISTING_ARCH="/var/asl/updates/modsec-*"
WGET1='wget --user="jim" --password="xxx-yyy-zzz" "http://updates.atomicorp.com/channels/rules/subscription/VERSION"'
WGET2='wget --user="jim" --password="xxx-yyy-zzz" "http://updates.atomicorp.com/channels/rules/subscription/modsec-$TARGET_DATE.tar.gz"'
## change to working directory and cleanup any downloaded files and extracted rules in modsec/ directory
cd $WORKING_DIR
rm -f $EXISTING_ARCH
rm -f $EXISTING_FILES
## wget1 to download VERSION file
`$WGET1`
## get current MODSEC_VERSION from VERSION file and save as variable
source VERSION
TARGET_DATE=`echo $MODSEC_VERSION`
## WGET2 command to download current archive
`$WGET2`
## extract archive
tar zxvf $WORKING_DIR/modsec-$TARGET_DATE.tar.gz
cp $EXISTING_FILES $TARGET_DIR
## restart server
exec '/usr/local/cpanel/scripts/restartsrv_httpd' $*;
Pro Tip: If you need string substitution, using ${VAR} is much better to eliminate ambiguity, e.g.:
tar zxvf $WORKING_DIR/modsec-${TARGET_DATE}.tar.gz
Let's say I have a very simple script which creates a link in a certain directory, and kills the script if it fails.
ln -s "/opt/myapp" "${1}/link" || exit 1;
Right now it just quits if it runs into errors. I want to change it so only if it runs into permission errors when creating the link, it will execute the following lines instead of exiting:
echo "The target directory requires root privileges to access."
sudo ln -s "/opt/myapp" "${1}/myapp" || exit 1;
I don't want to prompt the users to run as root unless they absolutely have to.
ln seems to retun exit code 1 on failure regardless of whether it was a problem with permissions or any other errors such as a directory not existing, so I can't use that to detect which problem it ran into.
And if I instead store search through the output of ln for the string "Permission denied", I'm assuming it will fail on non-english operating systems.
I don't know of any ways to categorize ln exit reasons, or at least any documentation about specific exit codes you could test with $?, but you can test for relevant permissions with the standard test or [ command:
SOURCEFILE="/opt/myapp"
DESTDIR="${1}"
DESTTARGET="${DESTDIR}/myapp"
if [ ! -d "$DESTDIR" -o ! -e "$SOURCEFILE" ]; then
echo "Source file does not exist or destination directory does not exist." >&2
elif [ ! -r "$SOURCEFILE" -o ! -w "$DESTDIR" ]; then
echo "Source file is not readable or destination directory is not writable." >&2
# Run sudo command here
else
# Should work, run command here
fi
I'm writing a bash script and want to do robust error checking in it.
The exit status code for mv to make it fail is easy to simulate a failure. All you have to do is move a file that doesn't exist, and it fails.
However with mkdir I want to simulate it failing. mkdir could fail for any number of reasons, problems with the disk, or lack of permissions, but not sure how to simulate a failure.
Just use
mkdir your_directory/
if [ $? -ne 0 ] ; then
echo "fatal"
else
echo "success"
fi
where $? stands for the exit code from the last command executed.
To create parent directories, when these don't exist, run mkdir -p parent_directory/your_directory/
if ! mkdir your_directory 2>/dev/null; then
print_error
exit
fi
or
mkdir your_directory 2>/dev/null || { print_error; exit; }
mkdir will fail if the directory already exists (unless you are using -p), and return an error code of 1 (on my system), so create the directory first to test this on your own system. (Although I would assume that is standard across all shells.)
Alternatively, make the parent directory read-only.
in your script , you could also put a check for the new dir ....
mkdir -p new_dir ;
if [ -d new_dir ]
cd new_dir && ...... anything else you want .
else
echo "error in directory creation ";
exit 2 ;
fi
If you are lazy a simple set -e in the beginning of you script is enough. Often you just want to print an error and then terminate if something goes wrong.
Not exactly what you asked for, but perhaps what you want.
I need help with two scripts I'm trying to make as one. There are two different ways to detect if there are issues with a bad NFS mount. One is if there is an issue, doing a df will hang and the other is the df works but there is are other issues with the mount which a find (mount name) -type -d will catch.
I'm trying to combine the scripts to catch both issues to where it runs the find type -d and if there is an issue, return an error. If the second NFS issue occurs and the find hangs, kill the find command after 2 seconds; run the second part of the script and if the NFS issue is occurring, then return an error. If neither type of NFS issue is occurring then return an OK.
MOUNTS="egrep -v '(^#)' /etc/fstab | grep nfs | awk '{print $2}'"
MOUNT_EXCLUDE=()
if [[ -z "${NFSdir}" ]] ; then
echo "Please define a mount point to be checked"
exit 3
fi
if [[ ! -d "${NFSdir}" ]] ; then
echo "NFS CRITICAL: mount point ${NFSdir} status: stale"
exit 2
fi
cat > "/tmp/.nfs" << EOF
#!/bin/sh
cd \$1 || { exit 2; }
exit 0;
EOF
chmod +x /tmp/.nfs
for i in ${NFSdir}; do
CHECK="ps -ef | grep "/tmp/.nfs $i" | grep -v grep | wc -l"
if [ $CHECK -gt 0 ]; then
echo "NFS CRITICAL : Stale NFS mount point $i"
exit $STATE_CRITICAL;
else
echo "NFS OK : NFS mount point $i status: healthy"
exit $STATE_OK;
fi
done
The MOUNTS and MOUNT_EXCLUDE lines are immaterial to this script as shown.
You've not clearly identified where ${NFSdir} is being set.
The first part of the script assumes ${NFSdir} contains a single directory value; the second part (the loop) assumes it may contain several values. Maybe this doesn't matter since the loop unconditionally exits the script on the first iteration, but it isn't the clear, clean way to write it.
You create the script /tmp/.nfs but:
You don't execute it.
You don't delete it.
You don't allow for multiple concurrent executions of this script by making a per-process file name (such as /tmp/.nfs.$$).
It is not clear why you hide the script in the /tmp directory with the . prefix to the name. It probably isn't a good idea.
Use:
tmpcmd=${TMPDIR:-/tmp}/nfs.$$
trap "rm -f $tmpcmd; exit 1" 0 1 2 3 13 15
...rest of script - modified to use the generated script...
rm -f $tmpcmd
trap 0
This gives you the maximum chance of cleaning up the temporary script.
There is no df left in the script, whereas the question implies there should be one. You should also look into the timeout command (though commands hung because NFS is not responding are generally very difficult to kill).