I am writing a script that locates a special type of file on my system and i want to check if those files are also present on a remote machine. So to test a single file I use: ssh -T user@host [[ -f /path/to/data/1/2/3/data.type ]] && echo "File exists" || echo "File does not exist"; But since I have to check blocks of 10 to 15 files, that i would like to check in one go, since I do not want to open a new ssh-connection for every file. My idea was to do something like: results=$(ssh "user@host" ' for file in "${@}"; do if [ -e "$file" ]; then echo "$file: exists" else echo "$file: does not exist" fi done ' "${files_list[@]}") Where the file list contains multiple file path. But this does not work, as a result, I would like to have the "echo" string for every file that was in the files_list.

Sometimes, a command is stalled attempting to write to a FIFO/pipe that no other process is currently reading from, but typing Ctrl-Z to put the process to the background by sending it the SIGTSTP signal (i.e. the *suspend* non-printing control character ^Z) does work. Example: $ mkfifo p $ ll p prw-rw-r-- 1 me me 0 Jul 30 16:27 p| $ echo "Go!" >p # Here & has been forgotten after the >p redirection (stalled) [Ctrl-Z] ^Z # Pressing Ctrl-Z just prints "^Z" on the terminal, nothing else happens [Ctrl-D] # Attempting to send the EOF character (nothing) # Doesn't print "^D" and does nothing and this is the behavior even though SIGTSTP (or susp) is reported to be attached to ^Z: $ stty -a speed 38400 baud; rows 24; columns 91; line = 0; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = ; eol2 = ; swtch = ; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; discard = ^O; min = 1; time = 0; -parenb -parodd -cmspar cs8 -hupcl -cstopb cread -clocal -crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -ixon -ixoff -iuclc -ixany -imaxbel iutf8 opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke -flusho -extproc How comes that in this case the terminal does not catch and transmit to the process the SIGTSTP signal generated by the Ctrl-Z? Is it because redirecting with > to a FIFO/pipe puts the terminal in raw mode (cf. The TTY demystified )? But if so, why does "^Z" get printed on the screen, and why Ctrl-D (EOF) doesn't print anything and yet doesn't have any effect either? Incidentally, is there an alternative way to send the stalled process to the background in such cases (instead of just terminate the process with Ctrl-C (i.e. ^C / SIGINT)?

Please see my linux bash script below. I can't achieve my target output with my current code. It keeps reading the whole column 4. input_file.txt: REV NUM |SVN PATH | FILE NAME |DOWNLOAD OPTIONS 1336 |svn/Repo/PROD | test2.txt |PROGRAM APPLICATION_SHORT_NAME="SQLGL" | 1334 |svn/Repo/PROD | test.txt |REQUEST_GROUP REQUEST_GROUP_NAME="Program Request Group" APPLICATION_SHORT_NAME="SQLGL" | my code: # /bin/bash REV_NUM=($(awk -F "|" 'NR>1 {print $1}' input_file.txt)) COMPONENT=($(awk -F "|" 'NR>1 {print $3}' input_file.txt)) DL_OPS="$(awk -F "|" 'NR>1 {print $4}' input_file.txt)" #LOOP REV_NUM_COUNT=${#REV_NUM[*]} for (( x=0 ; x<$REV_NUM_COUNT ; x++ )) do echo "${COMPONENT[x]} ${DL_OPS[x]}" done actual output: Exporting Component from SVN . . . test2.txt PROGRAM APPLICATION_SHORT_NAME="SQLGL" REQUEST_GROUP REQUEST_GROUP_NAME="Program Request Group" APPLICATION_SHORT_NAME="SQLGL" test.txt target output: Exporting Component from SVN . . . test2.txt PROGRAM APPLICATION_SHORT_NAME="SQLGL" test.txt REQUEST_GROUP REQUEST_GROUP_NAME="Program Request Group" APPLICATION_SHORT_NAME="SQLGL" Thank you so much

I want to write a bash script that would read a file with 2 columns f 2 g 1 s 4 d 5 f 2 g 5 d 9 g 10 h 1 s 5 d 29 My script would actually sort this file based on the first column (alphabet) and produce a file called alpha_sorted.txt and then I want it to do the same thing for the numbers and name it numbers_sorted.txt. The script is meant to be for introductory level so complicating the methods is not advised. ### Update Using john1024's answer, I have the following problem: Hasan@HasanChr /cygdrive/c/users/Hasan/Desktop/Bash $ chmod +x script.sh Hasan@HasanChr /cygdrive/c/users/Hasan/Desktop/Bash $ ./script.sh cat: alpha_sorted.txt: No such file or directory Here is a screenshot of script.sh

Wanted to run a script -- with option ./myscript.sh -a -g test -- without option ./myscript.sh -a -g The script looks like in below snippet, but don't see below script working correctly. The getopt for options specified with :: (like g:: or gamma::) upon parsing g or gamma the passed argument is moved to end every time includes empty argument user option: --gamma '' -a -- 'test'. Refer the output of the script

$ sh optionwithandwithoutarg.sh --gamma test -a
user option:  --gamma '' -a -- 'test'
arg info :- --gamma
arg info :- -a
arg info :- --
Alpha flag: true
Beta value: ''
Gamma value: 'default_gamma'
Remaining arguments: 'test'

## Script code used

#!/bin/bash

OPTIONS=$(getopt -o a,g::,b: --long alpha,gamma::,beta: --name "$0" -- "$@")

if [ $? -ne 0 ]; then
    echo "Error: Invalid options provided."
    exit 1
fi

echo "user option: $OPTIONS"

eval set -- "$OPTIONS"

# Initialize variables
ALPHA_FLAG="false"
BETA_VALUE=""
GAMMA_VALUE=""

while true; do
    echo "arg info :- $1"
    case "$1" in
        -a | --alpha)
            ALPHA_FLAG="true"
            shift
            ;;
        -b | --beta)
            BETA_VALUE="$2"
            shift 2
            ;;
        -g | --gamma)
            if [[ "$2" != "--" && -n "$2" ]]; then
                GAMMA_VALUE="$2"
                shift 2
            else
                GAMMA_VALUE="default_gamma" # Assign a default if no argument given
                shift 2
            fi
            ;;
        --)
            shift
            break
            ;;
        *)
            echo "Not supported option"
            exit 1
            ;;
    esac
done

echo "Alpha flag: $ALPHA_FLAG"
echo "Beta value: '$BETA_VALUE'"
echo "Gamma value: '$GAMMA_VALUE'"
echo "Remaining arguments: '$*'"

How to handle the options with and without argument with getopt

Both of them use bash, but the one used on arch linux has way better auto-completion. But why is that? Both of them claim to use normal Bash, so how can that be true? ---- I forgot to clarify that what I meant by Arch linux was it's installation ISO. I have never tried out the actual Arch linux. Also, I have tried ZSH and the auto-completion on ZSH seems similar to the arch bash's. Is it because of an additional package? --- The differences between Arch's Bash and Ubuntu's Bash is noticeable enough to understand what I'm talking about. Here is a little example: cat ./ (The command is not entered) - **Arch's Bash**: When I press TAB, all possible options are shown in a nice and very organized way, and when I press the down and up arrow keys, it allows me to select from those options. - **Ubuntu's Bash**: When I press TAB, all possible options are shown, sometimes in a nice and fairly organized way, but arrow keys just scroll between history of commands, not options. Not convenient. This is one way Arch's Bash is better than Ubuntu's Bash. This is assuming there are not too many options and around 16 options to choose from. Arch's ISO is the version released on July 2025.

I am running cmake and it is passing a flag to my linker that is unrecognized (-rdynamic), and it's causing an error. I cannot figure out where it is getting this flag from, so I want to just filter it out. I can specify -DCMAKE_LINKER=, so what I would like to do is set `` to a program that reads its command line arguments, filters out the bad one, and then passes the result back to the actual linker. I have been using awk '{gsub("-rdynamic", "");print}', but I don't know to make the input stdin and the output ld.

I like to use set -x in scripts to show what's going on, especially if the script is going to run in a CI/CD pipeline and I might need to debug some failure post-hoc. One annoyance with doing this is that if I want to echo some text to the user (e.g., a status message or "I'm starting to do $X") then that message gets output twice - once for the echo command itself being echoed, and then once as the output of that echo command. What's a good way to make this nicer? One solution is this:

set -x

... bunch of normal commands that get echoed

(
  # Temporarily don't echo, so we don't double-echo
  set +x
  echo "Here is my status message"
)

... rest of commands get echoed again

But the two problems with that are 1. That's a lot of machinery to write every time I want to tell the user something, and it's "non-obvious" enough that it probably requires the comment every time 2. It echoes the set +x too, which is undesirable. Is there another option that works well? Something like Make's feature of prepending an @ to suppress echoing would be great, but I've not been able to find such a feature in Bash.

Is there any variable that cron sets when it runs a program ? If the script is run by cron, I would like to skip some parts; otherwise invoke those parts. How can I know if the Bash script is started by cron ?

I have a shell script which sucessfully redirects all output to a log file and stdout (console) at the same time. However, when it exits it seems to wait for some user input from the keyboard (experimentally, any key seems to work)... So, I run the script, see the output, it exits and I have to hit e.g. the spacebar before the terminal prompt re-appears. Typing echo $? then gives the correct exit code. The basics of the script are: #!/bin/bash LOG="./test.log" rm -f $LOG exec > >(tee $LOG) 2>&1 if [[ "$1" = "T" ]]; then echo "twas true..." exit 0 else echo "twas false..." exit 100 fi Any help appreciated... not only do I not want to hit the spacebar but I would like to understand what is going on? ***Amendment***: it appears that I have to hit **enter** to get the terminal prompt back. From my limited experience using the *ps* command it would seem that my script has terminated and the *bash* shell is in the interruptible sleep state **S**. It would appear that maybe the terminal prompt output has been consumed or incorrectly redirected? I cannot see why...

I just noticed my environment is behaving erratically because at some point this alias got introduced in `/etc/profile.d/vim.sh`: $ command -v vim alias vim='__vi_internal_vim_alias' Looking through the files in `/etc/profile.d`, they’re of no use to me as everything I need is already taken care of in my `.bashrc`. As a consequence, Bash starts out in an unnecessarily polluted state after login. I’d like Bash to completely ignore the directory and just execute `.bashrc`. However, as the manpage states it will blindly source everything in that path before it continues with user controlled rc files. This is a corporate environment so I have no control over the OS just my user account. There’s an option `--noprofile` but I can’t seem to get it added to passwd: $ chsh Changing shell for philipp. New shell [/bin/bash] > /bin/bash --noprofile chsh: "/bin/bash --noprofile" does not exist Through SSH I could add `bash --noprofile` manually but that becomes tedious as I have dozens if not hundreds of SSH connections over the course of a regular workday. It would be ok if I could just make Bash forget those settings at the top of `.bashrc` and then continue with a clean environment. What I would prefer to avoid is having to play whack-a-mole with whatever definitions `/etc/profile.d` might possibly add on all the systems I’m using.

I need to export proxy on RHEL 7 with the current logged user credentials. I am able to achieve this by adding manually in **.bashrc or .bash_profile.**: export http_proxy=http://username:password@proxy.example.com:6080 export https_proxy=http://username:password@proxy.example.com:6080 The above method works fine. But I don't want this method, since we are hard-coding the username and password and also it's not secure. Is it possible to use the existing **/etc/shadow** file as password for exporting the proxy?

RHEL9 Sometimes server 1 has the secondary address 10.143.170.80/24, and sometimes server 2 has that secondary address. My script needs to test which server has that secondary address. However, ip address show dev ${VirtDev} secondary always returns 0, whether or not the secondary address exists or not. Server 1: ip address show dev $VirtDev secondary echo $? 0 Server 2: ip address show dev $VirtDev secondary 2: ens33: mtu 1500 qdisc mq state UP group default qlen 1000 link/ether 00:50:56:8e:73:35 brd ff:ff:ff:ff:ff:ff altname enp2s1 inet 10.143.170.80/24 scope global secondary ens33:0 valid_lft forever preferred_lft forever echo $? 0 This works, but seems janky: Exists=$(ip address show dev $VirtDev secondary) [ -n "$Exists" ] && echo exists || echo not exists Is there a better way? EDIT: when parsing json... ip -j -4 a ls to 10.143.170.80 | jq -e .[].addr_info [ {}, { "family": "inet", "local": "10.143.170.80", "prefixlen": 24, "scope": "global", "secondary": true, "label": "ens33:0", "valid_life_time": 4294967295, "preferred_life_time": 4294967295 } ] ip -j -4 a ls to 10.143.170.80 | jq -e .[].addr_info.local jq: error (at :1): Cannot index array with string "local"

I have an interesting case where I'm getting the below error when running a bash program but only when it's run via a systemd unit (running within Nixos). telegram: startProcess: posix_spawnp: does not exist (No such file or directory) If I run this program from the command line locally it works with no issue... What might be the cause of this error? It seems like posix_spawnp is actually a syscall which confuses me (why does the error seem to indicate it's an executable?) The actual script is located here: https://github.com/fabianonline/telegram.sh/blob/master/telegram

so trying to capture history with date and readable timestamps AND the command should appear on same line. following is failing: Bash ver is: GNU bash, version 4.4.20(1)-release (x86_64-redhat-linux-gnu) OS: RHEL 8.x in .bashrc.... setopt EXTENDED_HISTORY export HISTTIMEFORMAT='%F %I:%M:%S %T' #export HISTTIMEFORMAT="%F %T " export HISTSIZE=1000 export HISTFILE=$HOME/.bash_history-$USER export HISTFILESIZE=1000 export PROMPT_COMMAND='history -a' env variables: $ env|grep HIST HISTCONTROL=ignoredups HISTTIMEFORMAT=%F %I:%M:%S %T HISTFILE=/home/user1/.bash_history-user1 HISTSIZE=1000 HISTFILESIZE=1000 the records appear as: #1753745611 cd #1753745616 ls -ltra|tail #1753745626 cat .profile #1753745633 cat .kshrc **expected:** Mon Jul 28 23:33:31 GMT 2025 cd Mon Jul 28 23:33:36 GMT 2025 ls -ltra|tail Mon Jul 28 23:33:46 GMT 2025 cat .profile Mon Jul 28 23:33:53 GMT 2025 cat .kshrc two problems with this. 1. Timestamp appears in UNIX EPOCH format. 2. Timestamp and command appears on separate lines. They should be together. Also behaves the same way when using KSH. How can this be fixed? preferably using HISTTIMEFORMAT Thank you.

I'm trying to delete range of array element but it's fail.. My array root@ubuntu:~/work# echo ${a[@]} cocacola.com airtel.com pepsi.com Print 0-1 array looks ok root@ubuntu:~/work# echo ${a[@]::2} cocacola.com airtel.com Now I'm trying to delete only these element using : root@ubuntu:~/work# unset a[@]::2 root@ubuntu:~/work# echo ${a[@]} It's delete whole array.. What I'm doing wrong ? I found other way of deleting range of array but why above things is not working ? for ((i=0; i<2; i++)); do unset a[$i]; done EDIT I had also tried but no luck unset -v 'a[@]::2'

I'm trying to use Linux bash config on a mac. I don't use zsh only bash on my mac. I have problem with this variable:

# After each command, append to the history file and reread it
PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}history -a; history -c; history -r"

I'm not sure what is the source of this code, but i use it on Linux to keep all history from different terminal tabs in sync. But on mac I got empty history. I'm not sure if this something that was from the start after I added this to my .bashrc or something that appeared just now. I didn't notice any problems before, but I use mac only for few weeks, and I may not use history at all. I have fzf setup, but I may not use CTRL+R at all. And I'm not sure if I used up arrow. This is something that I don't pay much attention to, I do this automatically.

From a bash shell script, I am creating a folder and storing the mysqldump there. I am sure that there is no command related to permissions in my script. To allow an other user to access these files, I have used ACL, but when he tried to access the file, he got permission denied issue, and issue is with effective permissions of ACL. The owner of the directory is ola and new user who is trying to access the folder is uber and folder is gettaxi ### Permissions of Parent directory [/omega/olabooktmp]# getfacl . # file: . # owner: ola # group: ola user::rwx user:uber:rwx group::r-x mask::rwx other::r-x default:user::rwx default:user:uber:rwx default:group::r-x default:mask::rwx default:other::r-x ### Permissions of Child directory [/omega/olabooktemp]# getfacl gettaxi/ # file: gettaxi/ # owner: ola # group: ola user::rwx user:uber:rwx #effective:--- group::r-x #effective:--- mask::--- other::--- default:user::rwx default:user:uber:rwx default:group::r-x default:mask::rwx default:other::r-x I see like for new directory gettaxi mask permissions are mask::---, so I think this is causing issue, but I am unable to understand completely and how to solve this issue. Any suggestions greatly appreicated. Thank you.

With a netcat listener like: nc -l / > ~/.bashrc My question is: Is there a way to mimic the capabilities of nc -l in my first line with /dev/tcp instead of nc? The machines I'm working on are extremely hardened lab/sandbox environment RHEL (no ssh, no nc, no LDAP, no yum, I can't install new software, and they are not connected to the internet)

Does anybody know why this is happening and how to fix it?

me@box:~$ echo "eyJmb28iOiJiYXIiLCJiYXoiOiJiYXQifQ" | base64 -di
{"foo":"bar","baz":"bat"}base64: invalid input