Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty - Red Hat Enterprise Linux 9 Administration-Packt Publishing (2022) -chap 3 82 - 180
[root@rhel-instance ]# ls -m /var/ account, adm, cache, crash, db, empty, ftp, games, gopher, kerberos, lib, local, lock, log, mail, nis, opt, preserve, run, spool, tmp, yp Now, we run the command again, redirecting the output to the /root/var-files.txt file: [root@rhel-instance ]# ls m var > /root/var-files.txt [root@rhel-instance ]# As we can see, no output is shown onscreen, but we will be able to find the new file in the current working directory – in this case, root, the newly created file: [root@rhel-instance ]# ls /root anaconda-ks.cfg var-files.txt To seethe content of the file onscreen, we use the cat command, intended to concatenate the output for several files, but regularly used for this purpose: [root@rhel-instance ]# cat var-files.txt account adm, cache, crash, db, empty, ftp, games, gopher, kerberos, lib, local, lock, log, mail, nis, opt, preserve, run, spool, tmp, yp We can also add to this file the content of /var/lib. First, we can list it: [root@rhel-instance ]# ls -m /var/lib/ alternatives, authselect, chrony, dbus, dhclient, dnf, games, initramfs, logrotate, misc, NetworkManager, os-prober, plymouth, polkit-1, portables, private, rhsm, rpm, rpm-state, rsyslog, selinux, sss, systemd, tpm, tuned, unbound
Understanding IO redirection on the command line 79 Now, to append this content to the /root/var-files.txt file, we use the >> operator: [root@rhel-instance ]# ls -m /var/lib/ >> var-files.txt [root@rhel-instance ]# cat var-files.txt account, adm, cache, crash, db, empty, ftp, games, gopher, kerberos, lib, local, lock, log, mail, nis, opt, preserve, run, spool, tmp, yp alternatives, authselect, chrony, cni, containers, dnf, fprint,
